Sarbians changes to use object pooling and other techniques to reduce GC
Sarbians changes to use object pooling and other techniques to reduce GC

--- a/KerbalEngineer/EngineerGlobals.cs
+++ b/KerbalEngineer/EngineerGlobals.cs
@@ -33,7 +33,7 @@
         /// <summary>
         ///     Current version of the Kerbal Engineer assembly.
         /// </summary>
-        public const string AssemblyVersion = "1.0.15.2";
+        public const string AssemblyVersion = "1.0.16.0";
 
         #endregion
 

--- a/KerbalEngineer/Extensions/PartExtensions.cs
+++ b/KerbalEngineer/Extensions/PartExtensions.cs
@@ -83,11 +83,27 @@
         }
 
         /// <summary>
+        ///     Gets the cost of the part modules
+        ///     Same as stock but without mem allocation
+        /// </summary>
+        public static double GetModuleCostsNoAlloc(this Part part, float defaultCost)
+        {
+            float cost = 0f;
+            for (int i = 0; i < part.Modules.Count; i++)
+            {
+                PartModule pm = part.Modules[i];
+                if (pm is IPartCostModifier)
+                    cost += (pm as IPartCostModifier).GetModuleCost(defaultCost);
+            }
+            return cost;
+        }
+
+        /// <summary>
         ///     Gets the cost of the part including resources.
         /// </summary>
         public static double GetCostWet(this Part part)
         {
-            return part.partInfo.cost - GetResourceCostInverted(part) + part.GetModuleCosts(0.0f);
+            return part.partInfo.cost - GetResourceCostInverted(part) + part.GetModuleCostsNoAlloc(0.0f); // part.GetModuleCosts allocate 44B per call. 
         }
 
         /// <summary>
@@ -124,7 +140,13 @@
         /// </summary>
         public static T GetModule<T>(this Part part) where T : PartModule
         {
-            return part.Modules.OfType<T>().FirstOrDefault();
+            for (int i = 0; i < part.Modules.Count; i++)
+            {
+                PartModule pm = part.Modules[i];
+                if (pm is T)
+                    return (T)pm;
+            }
+            return null;
         }
 
         /// <summary>
@@ -264,7 +286,13 @@
         /// </summary>
         public static double GetResourceCostInverted(this Part part)
         {
-            return part.Resources.list.Sum(r => (r.maxAmount - r.amount) * r.info.unitCost);
+            double sum = 0;
+            for (int i = 0; i < part.Resources.list.Count; i++)
+            {
+                PartResource r = part.Resources.list[i];
+                sum += (r.maxAmount - r.amount) * r.info.unitCost;
+            }
+            return sum;
         }
 
         /// <summary>
@@ -309,7 +337,12 @@
         /// </summary>
         public static bool HasModule<T>(this Part part) where T : PartModule
         {
-            return part.Modules.OfType<T>().Any();
+            for (int i = 0; i < part.Modules.Count; i++)
+            {
+                if (part.Modules[i] is T)
+                    return true;
+            }
+            return false;
         }
 
         /// <summary>
@@ -317,7 +350,13 @@
         /// </summary>
         public static bool HasModule<T>(this Part part, Func<T, bool> predicate) where T : PartModule
         {
-            return part.Modules.OfType<T>().Any(predicate);
+            for (int i = 0; i < part.Modules.Count; i++)
+            {
+                PartModule pm = part.Modules[i];
+                if (pm is T && predicate(pm as T))
+                    return true;
+            }
+            return false;
         }
 
         /// <summary>
@@ -421,8 +460,9 @@
         /// </summary>
         public static bool IsPrimary(this Part part, List<Part> partsList, PartModule module)
         {
-            foreach (var vesselPart in partsList)
-            {
+            for (int i = 0; i < partsList.Count; i++)
+            {
+                var vesselPart = partsList[i];
                 if (!vesselPart.HasModule(module.ClassID))
                 {
                     continue;
@@ -464,7 +504,7 @@
         /// </summary>
         public static bool IsSolidRocket(this Part part)
         {
-            return part.HasModule<ModuleEngines>() && part.GetModuleEngines().throttleLocked;
+            return (part.HasModule<ModuleEngines>() && part.GetModuleEngines().throttleLocked) || (part.HasModule<ModuleEnginesFX>() && part.GetModuleEnginesFx().throttleLocked);
         }
 
         #endregion

--- a/KerbalEngineer/Helpers/Averager.cs
+++ b/KerbalEngineer/Helpers/Averager.cs
@@ -45,6 +45,12 @@
         private Vector3d sum = Vector3d.zero;
         private double totalweight = 0;
 
+        public void Reset()
+        {
+            sum = Vector3d.zero;
+            totalweight = 0;
+        }
+
         public void Add(Vector3d v, double weight) {
             sum += v * weight;
             totalweight += weight;

--- a/KerbalEngineer/Helpers/ForceAccumulator.cs
+++ b/KerbalEngineer/Helpers/ForceAccumulator.cs
@@ -19,16 +19,27 @@
 
 using System;
 using System.Collections.Generic;
+using KerbalEngineer.VesselSimulator;
+using Smooth.Pools;
 
 namespace KerbalEngineer
 {
     // a (force, application point) tuple
     public class AppliedForce
     {
+        public static readonly Pool<AppliedForce> pool = new Pool<AppliedForce>(Create, Reset);
+
         public Vector3d vector;
         public Vector3d applicationPoint;
 
-        public AppliedForce(Vector3d vector, Vector3d applicationPoint) {
+        static private AppliedForce Create()
+        {
+            return new AppliedForce();
+        }
+
+        static  private void Reset(AppliedForce appliedForce) { }
+
+        public void Set(Vector3d vector, Vector3d applicationPoint) {
             this.vector = vector;
             this.applicationPoint = applicationPoint;
         }
@@ -47,7 +58,7 @@
 	// some amount of residual torque. The line with the least amount of residual torque is chosen.
 	public class ForceAccumulator
 	{
-		// Total force.
+	    // Total force.
 		private Vector3d totalForce = Vector3d.zero;
 		// Torque needed to compensate if force were applied at origin.
 		private Vector3d totalZeroOriginTorque = Vector3d.zero;
@@ -99,5 +110,12 @@
         {
             return GetMinTorqueForceApplicationPoint(avgApplicationPoint.Get());
         }
+
+        public void Reset()
+        {
+            totalForce = Vector3d.zero;
+            totalZeroOriginTorque = Vector3d.zero;
+            avgApplicationPoint.Reset();
+        }
 	}
 }

--- a/KerbalEngineer/KerbalEngineer.csproj
+++ b/KerbalEngineer/KerbalEngineer.csproj
@@ -124,6 +124,11 @@
     <Compile Include="Helpers\TimeFormatter.cs" />
     <Compile Include="KeyBinder.cs" />
     <Compile Include="Control\ControlCentre.cs" />
+    <Compile Include="Smooth\Delegates\Delegates.cs" />
+    <Compile Include="Smooth\Dispose\Disposable.cs" />
+    <Compile Include="Smooth\Dispose\DisposalQueue.cs" />
+    <Compile Include="Smooth\Dispose\SmoothDisposer.cs" />
+    <Compile Include="Smooth\Pools\Pool.cs" />
     <Compile Include="UIControls\DropDown.cs" />
     <Compile Include="Logger.cs" />
     <Compile Include="EngineerGlobals.cs" />
@@ -207,7 +212,7 @@
   </ItemGroup>
   <ItemGroup>
     <Reference Include="Assembly-CSharp">
-      <HintPath>..\Game\KSP_Data\Managed\Assembly-CSharp.dll</HintPath>
+      <HintPath>..\..\..\..\..\..\KSP\Releases\Clean_0.90.0\KSP_Data\Managed\Assembly-CSharp.dll</HintPath>
       <Private>False</Private>
     </Reference>
     <Reference Include="System">
@@ -219,10 +224,11 @@
       <Private>False</Private>
     </Reference>
     <Reference Include="UnityEngine">
-      <HintPath>..\Game\KSP_Data\Managed\UnityEngine.dll</HintPath>
+      <HintPath>..\..\..\..\..\..\KSP\Releases\Clean_0.90.0\KSP_Data\Managed\UnityEngine.dll</HintPath>
       <Private>False</Private>
     </Reference>
   </ItemGroup>
+  <ItemGroup />
   <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
   <Target Name="PostBuildMacros">
     <GetAssemblyIdentity AssemblyFiles="$(TargetPath)">

--- a/KerbalEngineer/VesselSimulator/AttachNodeSim.cs
+++ b/KerbalEngineer/VesselSimulator/AttachNodeSim.cs
@@ -21,6 +21,7 @@
 
 using System;
 using System.Text;
+using Smooth.Pools;
 
 #endregion
 
@@ -28,16 +29,26 @@
 {
     internal class AttachNodeSim
     {
+
+        public static readonly Pool<AttachNodeSim> pool = new Pool<AttachNodeSim>(Create, Reset);
+
         public PartSim attachedPartSim;
         public String id;
         public AttachNode.NodeType nodeType;
 
-        public AttachNodeSim(PartSim partSim, String newId, AttachNode.NodeType newNodeType)
+        private static AttachNodeSim Create()
+        {
+            return new AttachNodeSim();
+        }
+
+        public void Set(PartSim partSim, String newId, AttachNode.NodeType newNodeType)
         {
             this.attachedPartSim = partSim;
             this.nodeType = newNodeType;
             this.id = newId;
         }
+
+        static private void Reset(AttachNodeSim attachNodeSim) { }
 
         public void DumpToBuffer(StringBuilder buffer)
         {

--- a/KerbalEngineer/VesselSimulator/EngineSim.cs
+++ b/KerbalEngineer/VesselSimulator/EngineSim.cs
@@ -23,7 +23,7 @@
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
-
+using Smooth.Pools;
 using UnityEngine;
 
 #endregion
@@ -32,20 +32,41 @@
 {
     public class EngineSim
     {
+        public static readonly Pool<EngineSim> pool = new Pool<EngineSim>(Create, Reset);
+
         private readonly ResourceContainer resourceConsumptions = new ResourceContainer();
 
         public double actualThrust = 0;
         public bool isActive = false;
         public double isp = 0;
         public PartSim partSim;
-        public List<AppliedForce> appliedForces;
+        public List<AppliedForce> appliedForces = new List<AppliedForce>();
 
         public double thrust = 0;
 
         // Add thrust vector to account for directional losses
         public Vector3 thrustVec;
 
-        public EngineSim(PartSim theEngine,
+        private static EngineSim Create()
+        {
+            return new EngineSim();
+        }
+
+        private static void Reset(EngineSim engineSim)
+        {
+            engineSim.resourceConsumptions.Reset();
+            engineSim.actualThrust = 0;
+            engineSim.isActive = false;
+            engineSim.isp = 0;
+            for (int i = 0; i < engineSim.appliedForces.Count; i++)
+            {
+                AppliedForce.pool.Release(engineSim.appliedForces[i]);
+            }
+            engineSim.appliedForces.Clear();
+            engineSim.thrust = 0;
+        }
+
+        public void Set(PartSim theEngine,
                          double atmosphere,
                          double velocity,
                          float maxThrust,
@@ -186,8 +207,9 @@
             }
 
             float flowMass = 0f;
-            foreach (Propellant propellant in propellants)
-            {
+            for (int i = 0; i < propellants.Count; i++)
+            {
+                Propellant propellant = propellants[i];
                 flowMass += propellant.ratio * ResourceContainer.GetResourceDensity(propellant.id);
             }
 
@@ -196,8 +218,9 @@
                 buffer.AppendFormat("flowMass = {0:g6}\n", flowMass);
             }
 
-            foreach (Propellant propellant in propellants)
-            {
+            for (int i = 0; i < propellants.Count; i++)
+            {
+                Propellant propellant = propellants[i];
                 if (propellant.name == "ElectricCharge" || propellant.name == "IntakeAir")
                 {
                     continue;
@@ -206,7 +229,12 @@
                 double consumptionRate = propellant.ratio * flowRate / flowMass;
                 if (SimManager.logOutput)
                 {
-                    buffer.AppendFormat("Add consumption({0}, {1}:{2:d}) = {3:g6}\n", ResourceContainer.GetResourceName(propellant.id), theEngine.name, theEngine.partId, consumptionRate);
+                    buffer.AppendFormat(
+                        "Add consumption({0}, {1}:{2:d}) = {3:g6}\n",
+                        ResourceContainer.GetResourceName(propellant.id),
+                        theEngine.name,
+                        theEngine.partId,
+                        consumptionRate);
                 }
                 this.resourceConsumptions.Add(propellant.id, consumptionRate);
             }
@@ -216,12 +244,16 @@
                 MonoBehaviour.print(buffer);
             }
 
-            appliedForces = new List<AppliedForce>();
             double thrustPerThrustTransform = thrust / thrustTransforms.Count;
-            foreach (Transform thrustTransform in thrustTransforms) {
+            for (int i = 0; i < thrustTransforms.Count; i++)
+            {
+                Transform thrustTransform = thrustTransforms[i];
                 Vector3d direction = thrustTransform.forward.normalized;
                 Vector3d position = thrustTransform.position;
-                appliedForces.Add(new AppliedForce(direction * thrustPerThrustTransform, position));
+
+                AppliedForce appliedForce = AppliedForce.pool.Borrow();
+                appliedForce.Set(direction * thrustPerThrustTransform, position);
+                appliedForces.Add(appliedForce);
             }
         }
 
@@ -230,50 +262,70 @@
             get { return this.resourceConsumptions; }
         }
 
+        // A dictionary to hold a set of parts for each resource
+        Dictionary<int, HashSet<PartSim>> sourcePartSets = new Dictionary<int, HashSet<PartSim>>();
+
+        Dictionary<int, HashSet<PartSim>> stagePartSets = new Dictionary<int, HashSet<PartSim>>();
+
+        HashSet<PartSim> visited = new HashSet<PartSim>();
+
         public bool SetResourceDrains(List<PartSim> allParts, List<PartSim> allFuelLines, HashSet<PartSim> drainingParts)
         {
             LogMsg log = null;
-
-            // A dictionary to hold a set of parts for each resource
-            Dictionary<int, HashSet<PartSim>> sourcePartSets = new Dictionary<int, HashSet<PartSim>>();
-
-            foreach (int type in this.resourceConsumptions.Types)
-            {
-                HashSet<PartSim> sourcePartSet = null;
+            
+            foreach (HashSet<PartSim> sourcePartSet in sourcePartSets.Values)
+            {
+                sourcePartSet.Clear();
+            }
+
+            for (int index = 0; index < this.resourceConsumptions.Types.Count; index++)
+            {
+                int type = this.resourceConsumptions.Types[index];
+
+                HashSet<PartSim> sourcePartSet;
+                if (!sourcePartSets.TryGetValue(type, out sourcePartSet))
+                {
+                    sourcePartSet = new HashSet<PartSim>();
+                    sourcePartSets.Add(type, sourcePartSet);
+                }
                 switch (ResourceContainer.GetResourceFlowMode(type))
                 {
                     case ResourceFlowMode.NO_FLOW:
                         if (this.partSim.resources[type] > SimManager.RESOURCE_MIN && this.partSim.resourceFlowStates[type] != 0)
                         {
-                            sourcePartSet = new HashSet<PartSim>();
+                            //sourcePartSet = new HashSet<PartSim>();
                             //MonoBehaviour.print("SetResourceDrains(" + name + ":" + partId + ") setting sources to just this");
                             sourcePartSet.Add(this.partSim);
                         }
                         break;
 
                     case ResourceFlowMode.ALL_VESSEL:
-                        foreach (PartSim aPartSim in allParts)
-                        {
+                        for (int i = 0; i < allParts.Count; i++)
+                        {
+                            PartSim aPartSim = allParts[i];
                             if (aPartSim.resources[type] > SimManager.RESOURCE_MIN && aPartSim.resourceFlowStates[type] != 0)
                             {
-                                if (sourcePartSet == null)
-                                {
-                                    sourcePartSet = new HashSet<PartSim>();
-                                }
-
                                 sourcePartSet.Add(aPartSim);
                             }
                         }
                         break;
 
                     case ResourceFlowMode.STAGE_PRIORITY_FLOW:
-                        var stagePartSets = new Dictionary<int, HashSet<PartSim>>();
+
+                        foreach (HashSet<PartSim> stagePartSet in stagePartSets.Values)
+                        {
+                            stagePartSet.Clear();
+                        }
                         var maxStage = -1;
 
                         //Logger.Log(type);
-                        foreach (var aPartSim in allParts)
-                        {
-                            if (aPartSim.resources[type] <= SimManager.RESOURCE_MIN || aPartSim.resourceFlowStates[type] == 0) continue;
+                        for (int i = 0; i < allParts.Count; i++)
+                        {
+                            var aPartSim = allParts[i];
+                            if (aPartSim.resources[type] <= SimManager.RESOURCE_MIN || aPartSim.resourceFlowStates[type] == 0)
+                            {
+                                continue;
+                            }
 
                             var stage = aPartSim.DecouplerCount();
                             if (stage > maxStage)
@@ -281,9 +333,11 @@
                                 maxStage = stage;
                             }
 
-                            if (!stagePartSets.TryGetValue(stage, out sourcePartSet))
-                            {
-                                sourcePartSet = new HashSet<PartSim>();
+                            if (!stagePartSets.TryGetValue(stage, out sourcePartSet) || sourcePartSet.Count == 0)
+                            {
+                                if (sourcePartSet == null)
+                                    sourcePartSet = new HashSet<PartSim>();
+
                                 stagePartSets.Add(stage, sourcePartSet);
                             }
                             sourcePartSet.Add(aPartSim);
@@ -300,14 +354,16 @@
                         break;
 
                     case ResourceFlowMode.STACK_PRIORITY_SEARCH:
-                        HashSet<PartSim> visited = new HashSet<PartSim>();
+                        visited.Clear();
 
                         if (SimManager.logOutput)
                         {
                             log = new LogMsg();
-                            log.buf.AppendLine("Find " + ResourceContainer.GetResourceName(type) + " sources for " + this.partSim.name + ":" + this.partSim.partId);
-                        }
-                        sourcePartSet = this.partSim.GetSourceSet(type, allParts, visited, log, "");
+                            log.buf.AppendLine(
+                                "Find " + ResourceContainer.GetResourceName(type) + " sources for " + this.partSim.name + ":" +
+                                this.partSim.partId);
+                        }
+                        this.partSim.GetSourceSet(type, allParts, visited, sourcePartSet, log, "");
                         if (SimManager.logOutput)
                         {
                             MonoBehaviour.print(log.buf);
@@ -315,11 +371,14 @@
                         break;
 
                     default:
-                        MonoBehaviour.print("SetResourceDrains(" + this.partSim.name + ":" + this.partSim.partId + ") Unexpected flow type for " + ResourceContainer.GetResourceName(type) + ")");
+                        MonoBehaviour.print(
+                            "SetResourceDrains(" + this.partSim.name + ":" + this.partSim.partId + ") Unexpected flow type for " +
+                            ResourceContainer.GetResourceName(type) + ")");
                         break;
                 }
 
-                if (sourcePartSet != null && sourcePartSet.Count > 0)
+
+                if (sourcePartSet.Count > 0)
                 {
                     sourcePartSets[type] = sourcePartSet;
                     if (SimManager.logOutput)
@@ -334,11 +393,13 @@
                     }
                 }
             }
-
+            
             // If we don't have sources for all the needed resources then return false without setting up any drains
-            foreach (int type in this.resourceConsumptions.Types)
-            {
-                if (!sourcePartSets.ContainsKey(type))
+            for (int i = 0; i < this.resourceConsumptions.Types.Count; i++)
+            {
+                int type = this.resourceConsumptions.Types[i];
+                HashSet<PartSim> sourcePartSet; 
+                if (!sourcePartSets.TryGetValue(type, out sourcePartSet) || sourcePartSet.Count() == 0)
                 {
                     if (SimManager.logOutput)
                     {
@@ -349,10 +410,10 @@
                     return false;
                 }
             }
-
             // Now we set the drains on the members of the sets and update the draining parts set
-            foreach (int type in this.resourceConsumptions.Types)
-            {
+            for (int i = 0; i < this.resourceConsumptions.Types.Count; i++)
+            {
+                int type = this.resourceConsumptions.Types[i];
                 HashSet<PartSim> sourcePartSet = sourcePartSets[type];
                 // Loop through the members of the set 
                 double amount = this.resourceConsumptions[type] / sourcePartSet.Count;
@@ -360,14 +421,15 @@
                 {
                     if (SimManager.logOutput)
                     {
-                        MonoBehaviour.print("Adding drain of " + amount + " " + ResourceContainer.GetResourceName(type) + " to " + partSim.name + ":" + partSim.partId);
+                        MonoBehaviour.print(
+                            "Adding drain of " + amount + " " + ResourceContainer.GetResourceName(type) + " to " + partSim.name + ":" +
+                            partSim.partId);
                     }
 
                     partSim.resourceDrains.Add(type, amount);
                     drainingParts.Add(partSim);
                 }
             }
-
             return true;
         }
 

--- a/KerbalEngineer/VesselSimulator/PartSim.cs
+++ b/KerbalEngineer/VesselSimulator/PartSim.cs
@@ -25,7 +25,7 @@
 using System.Text;
 
 using KerbalEngineer.Extensions;
-
+using Smooth.Pools;
 using UnityEngine;
 
 #endregion
@@ -36,7 +36,10 @@
 
     public class PartSim
     {
+        public static readonly Pool<PartSim> pool = new Pool<PartSim>(Create, Reset);
+
         private readonly List<AttachNodeSim> attachNodes = new List<AttachNodeSim>();
+
         public Vector3d centerOfMass;
         public double baseMass = 0d;
         public double cost;
@@ -70,8 +73,29 @@
         public double startMass = 0d;
         public String vesselName;
         public VesselType vesselType;
-
-        public PartSim(Part thePart, int id, double atmosphere, LogMsg log)
+        
+
+        private static PartSim Create()
+        {
+            return new PartSim();
+        }
+
+        private static void Reset(PartSim partSim)
+        {
+            for (int i = 0; i < partSim.attachNodes.Count; i++)
+            {
+                AttachNodeSim.pool.Release(partSim.attachNodes[i]);
+            }
+            partSim.attachNodes.Clear();
+            partSim.fuelTargets.Clear();
+            partSim.resourceDrains.Reset();
+            partSim.resourceFlowStates.Reset();
+            partSim.resources.Reset();
+            partSim.baseMass = 0d;
+            partSim.startMass = 0d;
+        }
+
+        public void Set(Part thePart, int id, double atmosphere, LogMsg log)
         {
             this.part = thePart;
             this.centerOfMass = thePart.transform.TransformPoint(thePart.CoMOffset);
@@ -111,8 +135,10 @@
                 MonoBehaviour.print((this.isNoPhysics ? "Ignoring" : "Using") + " part.mass of " + this.part.mass);
             }
 
-            foreach (PartResource resource in this.part.Resources)
-            {
+            for (int i = 0; i < this.part.Resources.Count; i++)
+            {
+                PartResource resource = this.part.Resources[i];
+
                 // Make sure it isn't NaN as this messes up the part mass and hence most of the values
                 // This can happen if a resource capacity is 0 and tweakable
                 if (!Double.IsNaN(resource.amount))
@@ -170,9 +196,9 @@
             if (log != null)
             {
                 log.buf.AppendLine("CreateEngineSims for " + this.name);
-
-                foreach (PartModule partMod in this.part.Modules)
-                {
+                for (int i = 0; i < this.part.Modules.Count; i++)
+                {
+                    PartModule partMod = this.part.Modules[i];
                     log.buf.AppendLine("Module: " + partMod.moduleName);
                 }
 
@@ -185,8 +211,10 @@
                 // The mode of the engine is the engineID of the ModuleEnginesFX that is active
                 string mode = this.part.GetModule<MultiModeEngine>().mode;
 
-                foreach (ModuleEnginesFX engine in this.part.GetModules<ModuleEnginesFX>())
-                {
+                List<ModuleEnginesFX> enginesFx = this.part.GetModules<ModuleEnginesFX>();
+                for (int i = 0; i < enginesFx.Count; i++)
+                {
+                    ModuleEnginesFX engine = enginesFx[i];
                     if (engine.engineID == mode)
                     {
                         if (log != null)
@@ -196,22 +224,24 @@
 
                         Vector3 thrustvec = this.CalculateThrustVector(vectoredThrust ? engine.thrustTransforms : null, log);
 
-                        EngineSim engineSim = new EngineSim(this,
-                                                            atmosphere,
-                                                            velocity,
-                                                            engine.maxThrust,
-                                                            engine.minThrust,
-                                                            engine.thrustPercentage,
-                                                            engine.requestedThrust,
-                                                            thrustvec,
-                                                            engine.realIsp,
-                                                            engine.atmosphereCurve,
-                                                            engine.useVelocityCurve ? engine.velocityCurve : null,
-                                                            engine.throttleLocked,
-                                                            engine.propellants,
-                                                            engine.isOperational,
-                                                            correctThrust,
-                                                            engine.thrustTransforms);
+                        EngineSim engineSim = EngineSim.pool.Borrow();
+                        engineSim.Set(
+                            this,
+                            atmosphere,
+                            velocity,
+                            engine.maxThrust,
+                            engine.minThrust,
+                            engine.thrustPercentage,
+                            engine.requestedThrust,
+                            thrustvec,
+                            engine.realIsp,
+                            engine.atmosphereCurve,
+                            engine.useVelocityCurve ? engine.velocityCurve : null,
+                            engine.throttleLocked,
+                            engine.propellants,
+                            engine.isOperational,
+                            correctThrust,
+                            engine.thrustTransforms);
                         allEngines.Add(engineSim);
                     }
                 }
@@ -220,8 +250,10 @@
             {
                 if (this.hasModuleEnginesFX)
                 {
-                    foreach (ModuleEnginesFX engine in this.part.GetModules<ModuleEnginesFX>())
-                    {
+                    List<ModuleEnginesFX> enginesFx = this.part.GetModules<ModuleEnginesFX>();  // only place that still allocate some memory
+                    for (int i = 0; i < enginesFx.Count; i++)
+                    {
+                        ModuleEnginesFX engine = enginesFx[i];
                         if (log != null)
                         {
                             log.buf.AppendLine("Module: " + engine.moduleName);
@@ -229,30 +261,34 @@
 
                         Vector3 thrustvec = this.CalculateThrustVector(vectoredThrust ? engine.thrustTransforms : null, log);
 
-                        EngineSim engineSim = new EngineSim(this,
-                                                            atmosphere,
-                                                            velocity,
-                                                            engine.maxThrust,
-                                                            engine.minThrust,
-                                                            engine.thrustPercentage,
-                                                            engine.requestedThrust,
-                                                            thrustvec,
-                                                            engine.realIsp,
-                                                            engine.atmosphereCurve,
-                                                            engine.useVelocityCurve ? engine.velocityCurve : null,
-                                                            engine.throttleLocked,
-                                                            engine.propellants,
-                                                            engine.isOperational,
-                                                            correctThrust,
-                                                            engine.thrustTransforms);
+                        EngineSim engineSim = EngineSim.pool.Borrow();
+                        engineSim.Set(
+                            this,
+                            atmosphere,
+                            velocity,
+                            engine.maxThrust,
+                            engine.minThrust,
+                            engine.thrustPercentage,
+                            engine.requestedThrust,
+                            thrustvec,
+                            engine.realIsp,
+                            engine.atmosphereCurve,
+                            engine.useVelocityCurve ? engine.velocityCurve : null,
+                            engine.throttleLocked,
+                            engine.propellants,
+                            engine.isOperational,
+                            correctThrust,
+                            engine.thrustTransforms);
                         allEngines.Add(engineSim);
                     }
                 }
 
                 if (this.hasModuleEngines)
                 {
-                    foreach (ModuleEngines engine in this.part.GetModules<ModuleEngines>())
-                    {
+                    List<ModuleEngines> engines = this.part.GetModules<ModuleEngines>();  // only place that still allocate some memory
+                    for (int i = 0; i < engines.Count; i++)
+                    {
+                        ModuleEngines engine = engines[i];
                         if (log != null)
                         {
                             log.buf.AppendLine("Module: " + engine.moduleName);
@@ -260,22 +296,24 @@
 
                         Vector3 thrustvec = this.CalculateThrustVector(vectoredThrust ? engine.thrustTransforms : null, log);
 
-                        EngineSim engineSim = new EngineSim(this,
-                                                            atmosphere,
-                                                            velocity,
-                                                            engine.maxThrust,
-                                                            engine.minThrust,
-                                                            engine.thrustPercentage,
-                                                            engine.requestedThrust,
-                                                            thrustvec,
-                                                            engine.realIsp,
-                                                            engine.atmosphereCurve,
-                                                            engine.useVelocityCurve ? engine.velocityCurve : null,
-                                                            engine.throttleLocked,
-                                                            engine.propellants,
-                                                            engine.isOperational,
-                                                            correctThrust,
-                                                            engine.thrustTransforms);
+                        EngineSim engineSim = EngineSim.pool.Borrow();
+                        engineSim.Set(
+                            this,
+                            atmosphere,
+                            velocity,
+                            engine.maxThrust,
+                            engine.minThrust,
+                            engine.thrustPercentage,
+                            engine.requestedThrust,
+                            thrustvec,
+                            engine.realIsp,
+                            engine.atmosphereCurve,
+                            engine.useVelocityCurve ? engine.velocityCurve : null,
+                            engine.throttleLocked,
+                            engine.propellants,
+                            engine.isOperational,
+                            correctThrust,
+                            engine.thrustTransforms);
                         allEngines.Add(engineSim);
                     }
                 }
@@ -295,11 +333,17 @@
             }
 
             Vector3 thrustvec = Vector3.zero;
-            foreach (Transform trans in thrustTransforms)
-            {
+            for (int i = 0; i < thrustTransforms.Count; i++)
+            {
+                Transform trans = thrustTransforms[i];
                 if (log != null)
                 {
-                    log.buf.AppendFormat("Transform = ({0:g6}, {1:g6}, {2:g6})   length = {3:g6}\n", trans.forward.x, trans.forward.y, trans.forward.z, trans.forward.magnitude);
+                    log.buf.AppendFormat(
+                        "Transform = ({0:g6}, {1:g6}, {2:g6})   length = {3:g6}\n",
+                        trans.forward.x,
+                        trans.forward.y,
+                        trans.forward.z,
+                        trans.forward.magnitude);
                 }
 
                 thrustvec -= trans.forward;
@@ -350,11 +394,14 @@
             }
 
             this.attachNodes.Clear();
-            foreach (AttachNode attachNode in this.part.attachNodes)
-            {
+            for (int i = 0; i < this.part.attachNodes.Count; i++)
+            {
+                AttachNode attachNode = this.part.attachNodes[i];
                 if (log != null)
                 {
-                    log.buf.AppendLine("AttachNode " + attachNode.id + " = " + (attachNode.attachedPart != null ? attachNode.attachedPart.partInfo.name : "null"));
+                    log.buf.AppendLine(
+                        "AttachNode " + attachNode.id + " = " +
+                        (attachNode.attachedPart != null ? attachNode.attachedPart.partInfo.name : "null"));
                 }
 
                 if (attachNode.attachedPart != null && attachNode.id != "Strut")
@@ -367,7 +414,9 @@
                             log.buf.AppendLine("Adding attached node " + attachedSim.name + ":" + attachedSim.partId + "");
                         }
 
-                        this.attachNodes.Add(new AttachNodeSim(attachedSim, attachNode.id, attachNode.nodeType));
+                        AttachNodeSim attachnode = AttachNodeSim.pool.Borrow();
+                        attachnode.Set(attachedSim, attachNode.id, attachNode.nodeType);
+                        this.attachNodes.Add(attachnode);
                     }
                     else
                     {
@@ -379,8 +428,9 @@
                 }
             }
 
-            foreach (Part p in this.part.fuelLookupTargets)
-            {
+            for (int i = 0; i < this.part.fuelLookupTargets.Count; i++)
+            {
+                Part p = this.part.fuelLookupTargets[i];
                 if (p != null)
                 {
                     PartSim targetSim;
@@ -446,18 +496,13 @@
                 return true;
             }
 
-            var modList = this.part.Modules.OfType<ModuleEngines>();
-            if (modList.Count() == 0)
+            if (!this.part.IsEngine())
             {
                 return false;
             }
 
-            if (modList.First().throttleLocked)
-            {
-                return true;
-            }
-
-            return false;
+
+            return this.part.IsSolidRocket();
         }
 
         public void ReleasePart()
@@ -468,7 +513,7 @@
         // All functions below this point must not rely on the part member (it may be null)
         //
 
-        public HashSet<PartSim> GetSourceSet(int type, List<PartSim> allParts, HashSet<PartSim> visited, LogMsg log, String indent)
+        public void GetSourceSet(int type, List<PartSim> allParts, HashSet<PartSim> visited, HashSet<PartSim> allSources, LogMsg log, String indent)
         {
             if (log != null)
             {
@@ -476,10 +521,7 @@
                 indent += "  ";
             }
 
-            HashSet<PartSim> allSources = new HashSet<PartSim>();
-            HashSet<PartSim> partSources = null;
-
-            // Rule 1: Each part can be only visited once, If it is visited for second time in particular search it returns empty list.
+            // Rule 1: Each part can be only visited once, If it is visited for second time in particular search it returns as is.
             if (visited.Contains(this))
             {
                 if (log != null)
@@ -487,7 +529,7 @@
                     log.buf.AppendLine(indent + "Returning empty set, already visited (" + this.name + ":" + this.partId + ")");
                 }
 
-                return allSources;
+                return;
             }
 
             //if (log != null)
@@ -499,8 +541,11 @@
             // Then it makes an union of fuel tank sets each pipe scan returned. If the resulting list is not empty, it is returned as result.
             //MonoBehaviour.print("foreach fuel line");
 
-            foreach (PartSim partSim in this.fuelTargets)
-            {
+            int lastCount = allSources.Count;
+
+            for (int i = 0; i < this.fuelTargets.Count; i++)
+            {
+                PartSim partSim = this.fuelTargets[i];
                 if (visited.Contains(partSim))
                 {
                     //if (log != null)
@@ -511,24 +556,20 @@
                     //if (log != null)
                     //    log.buf.AppendLine(indent + "Adding fuel target as source (" + partSim.name + ":" + partSim.partId + ")");
 
-                    partSources = partSim.GetSourceSet(type, allParts, visited, log, indent);
-                    if (partSources.Count > 0)
-                    {
-                        allSources.UnionWith(partSources);
-                        partSources.Clear();
-                    }
-                }
-            }
-
-            if (allSources.Count > 0)
+                    partSim.GetSourceSet(type, allParts, visited, allSources, log, indent);
+                }
+            }
+
+            if (allSources.Count > lastCount)
             {
                 if (log != null)
                 {
-                    log.buf.AppendLine(indent + "Returning " + allSources.Count + " fuel target sources (" + this.name + ":" + this.partId + ")");
-                }
-
-                return allSources;
-            }
+                    log.buf.AppendLine(indent + "Returning " + (allSources.Count - lastCount) + " fuel target sources (" + this.name + ":" + this.partId + ")");
+                }
+
+                return;
+            }
+
 
             // Rule 3: This rule has been removed and merged with rules 4 and 7 to fix issue with fuel tanks with disabled crossfeed
 
@@ -539,14 +580,18 @@
             //  The order in which mount points of a part are scanned appears to be fixed and defined by the part specification file. [Experiment]
             if (this.fuelCrossFeed)
             {
+                lastCount = allSources.Count;
                 //MonoBehaviour.print("foreach attach node");
-                foreach (AttachNodeSim attachSim in this.attachNodes)
-                {
+                for (int i = 0; i < this.attachNodes.Count; i++)
+                {
+                    AttachNodeSim attachSim = this.attachNodes[i];
                     if (attachSim.attachedPartSim != null)
                     {
                         if (attachSim.nodeType == AttachNode.NodeType.Stack)
                         {
-                            if (!(this.noCrossFeedNodeKey != null && this.noCrossFeedNodeKey.Length > 0 && attachSim.id.Contains(this.noCrossFeedNodeKey)))
+                            if (
+                                !(this.noCrossFeedNodeKey != null && this.noCrossFeedNodeKey.Length > 0 &&
+                                  attachSim.id.Contains(this.noCrossFeedNodeKey)))
                             {
                                 if (visited.Contains(attachSim.attachedPartSim))
                                 {
@@ -558,26 +603,21 @@
                                     //if (log != null)
                                     //    log.buf.AppendLine(indent + "Adding attached part as source (" + attachSim.attachedPartSim.name + ":" + attachSim.attachedPartSim.partId + ")");
 
-                                    partSources = attachSim.attachedPartSim.GetSourceSet(type, allParts, visited, log, indent);
-                                    if (partSources.Count > 0)
-                                    {
-                                        allSources.UnionWith(partSources);
-                                        partSources.Clear();
-                                    }
+                                    attachSim.attachedPartSim.GetSourceSet(type, allParts, visited, allSources, log, indent);
                                 }
                             }
                         }
                     }
                 }
 
-                if (allSources.Count > 0)
+                if (allSources.Count > lastCount)
                 {
                     if (log != null)
                     {
-                        log.buf.AppendLine(indent + "Returning " + allSources.Count + " attached sources (" + this.name + ":" + this.partId + ")");
-                    }
-
-                    return allSources;
+                        log.buf.AppendLine(indent + "Returning " + (allSources.Count - lastCount) + " attached sources (" + this.name + ":" + this.partId + ")");
+                    }
+
+                    return;
                 }
             }
 
@@ -597,7 +637,7 @@
                     }
                 }
 
-                return allSources;
+                return;
             }
 
             // Rule 7: If the part is radially attached to another part and it is child of that part in the ship's tree structure, it scans its 
@@ -613,15 +653,16 @@
                     }
                     else
                     {
-                        allSources = this.parent.GetSourceSet(type, allParts, visited, log, indent);
-                        if (allSources.Count > 0)
+                        lastCount = allSources.Count;
+                        this.parent.GetSourceSet(type, allParts, visited, allSources, log, indent);
+                        if (allSources.Count > lastCount)
                         {
                             if (log != null)
                             {
-                                log.buf.AppendLine(indent + "Returning " + allSources.Count + " parent sources (" + this.name + ":" + this.partId + ")");
+                                log.buf.AppendLine(indent + "Returning " + (allSources.Count  - lastCount) + " parent sources (" + this.name + ":" + this.partId + ")");
                             }
 
-                            return allSources;
+                            return;
                         }
                     }
                 }
@@ -631,14 +672,15 @@
             //if (log != null)
             //    log.buf.AppendLine(indent + "Returning empty set, no sources found (" + name + ":" + partId + ")");
 
-            return allSources;
+            return;
         }
 
         public void RemoveAttachedParts(HashSet<PartSim> partSims)
         {
             // Loop through the attached parts
-            foreach (AttachNodeSim attachSim in this.attachNodes)
-            {
+            for (int i = 0; i < this.attachNodes.Count; i++)
+            {
+                AttachNodeSim attachSim = this.attachNodes[i];
                 // If the part is in the set then "remove" it by clearing the PartSim reference
                 if (partSims.Contains(attachSim.attachedPartSim))
                 {
@@ -650,8 +692,9 @@
         public void DrainResources(double time)
         {
             //MonoBehaviour.print("DrainResources(" + name + ":" + partId + ", " + time + ")");
-            foreach (int type in this.resourceDrains.Types)
-            {
+            for (int i = 0; i < this.resourceDrains.Types.Count; i++)
+            {
+                int type = this.resourceDrains.Types[i];
                 //MonoBehaviour.print("draining " + (time * resourceDrains[type]) + " " + ResourceContainer.GetResourceName(type));
                 this.resources.Add(type, -time * this.resourceDrains[type]);
                 //MonoBehaviour.print(ResourceContainer.GetResourceName(type) + " left = " + resources[type]);
@@ -663,8 +706,9 @@
             //MonoBehaviour.print("TimeToDrainResource(" + name + ":" + partId + ")");
             double time = double.MaxValue;
 
-            foreach (int type in this.resourceDrains.Types)
-            {
+            for (int i = 0; i < this.resourceDrains.Types.Count; i++)
+            {
+                int type = this.resourceDrains.Types[i];
                 if (this.resourceDrains[type] > 0)
                 {
                     time = Math.Min(time, this.resources[type] / this.resourceDrains[type]);
@@ -715,8 +759,9 @@
         {
             double mass = this.baseMass;
 
-            foreach (int type in this.resources.Types)
-            {
+            for (int i = 0; i < this.resources.Types.Count; i++)
+            {
+                int type = this.resources.Types[i];
                 mass += this.resources.GetResourceMass(type);
             }
 
@@ -750,8 +795,9 @@
 
             buffer.AppendFormat(", isSep = {0}", this.isSepratron);
 
-            foreach (int type in this.resources.Types)
-            {
+            for (int i = 0; i < this.resources.Types.Count; i++)
+            {
+                int type = this.resources.Types[i];
                 buffer.AppendFormat(", {0} = {1:g6}", ResourceContainer.GetResourceName(type), this.resources[type]);
             }
 
@@ -774,8 +820,9 @@
             if (allParts != null)
             {
                 String newPrefix = prefix + " ";
-                foreach (PartSim partSim in allParts)
-                {
+                for (int i = 0; i < allParts.Count; i++)
+                {
+                    PartSim partSim = allParts[i];
                     if (partSim.parent == this)
                     {
                         partSim.DumpPartToBuffer(buffer, newPrefix, allParts);

--- a/KerbalEngineer/VesselSimulator/ResourceContainer.cs
+++ b/KerbalEngineer/VesselSimulator/ResourceContainer.cs
@@ -19,6 +19,7 @@
 
 #region Using Directives
 
+using System;
 using System.Collections;
 using System.Collections.Generic;
 
@@ -30,15 +31,17 @@
 {
     public class ResourceContainer
     {
-        private Hashtable resources = new Hashtable();
+        private Dictionary<int, double> resources = new Dictionary<int, double>();
+        private List<int> types = new List<int>();
 
         public double this[int type]
         {
             get
             {
-                if (this.resources.ContainsKey(type))
+                double value;
+                if (this.resources.TryGetValue(type, out value))
                 {
-                    return (double)this.resources[type];
+                    return value;
                 }
 
                 return 0d;
@@ -52,6 +55,7 @@
                 else
                 {
                     this.resources.Add(type, value);
+                    this.types.Add(type);
                 }
             }
         }
@@ -60,13 +64,6 @@
         {
             get
             {
-                List<int> types = new List<int>();
-
-                foreach (int key in this.resources.Keys)
-                {
-                    types.Add(key);
-                }
-
                 return types;
             }
         }
@@ -92,7 +89,7 @@
             {
                 foreach (int type in this.resources.Keys)
                 {
-                    if ((double)this.resources[type] > SimManager.RESOURCE_MIN)
+                    if (this.resources[type] > SimManager.RESOURCE_MIN)
                     {
                         return false;
                     }
@@ -111,7 +108,7 @@
         {
             foreach (int type in types)
             {
-                if (this.HasType(type) && (double)this.resources[type] > SimManager.RESOURCE_MIN)
+                if (this.HasType(type) && this.resources[type] > SimManager.RESOURCE_MIN)
                 {
                     return false;
                 }
@@ -124,17 +121,19 @@
         {
             if (this.resources.ContainsKey(type))
             {
-                this.resources[type] = (double)this.resources[type] + amount;
+                this.resources[type] = this.resources[type] + amount;
             }
             else
             {
                 this.resources.Add(type, amount);
+                this.types.Add(type);
             }
         }
 
         public void Reset()
         {
-            this.resources = new Hashtable();
+            this.resources.Clear();
+            this.types.Clear();
         }
 
         public void Debug()
@@ -148,7 +147,7 @@
         public double GetResourceMass(int type)
         {
             double density = GetResourceDensity(type);
-            return density == 0d ? 0d : (double)this.resources[type] * density;
+            return density == 0d ? 0d : this.resources[type] * density;
         }
 
         public static ResourceFlowMode GetResourceFlowMode(int type)
@@ -158,7 +157,7 @@
 
         public static ResourceTransferMode GetResourceTransferMode(int type)
         {
-            return PartResourceLibrary.Instance.GetDefinition(type).resourceTransferMode;
+            return PartResourceLibrary.Instance.GetDefinition(type).resourceTransferMode;;
         }
 
         public static float GetResourceDensity(int type)

--- a/KerbalEngineer/VesselSimulator/Simulation.cs
+++ b/KerbalEngineer/VesselSimulator/Simulation.cs
@@ -45,11 +45,14 @@
         private double atmosphere;
         private int currentStage;
         private double currentisp;
+        private HashSet<PartSim> decoupledParts = new HashSet<PartSim>();
         private bool doingCurrent;
         private List<PartSim> dontStageParts;
+        private List<List<PartSim>> dontStagePartsLists = new List<List<PartSim>>();
         private HashSet<PartSim> drainingParts;
         private HashSet<int> drainingResources;
         private double gravity;
+        private Dictionary<Part, PartSim> partSimLookup;
 
         private int lastStage;
         private List<Part> partList;
@@ -73,6 +76,17 @@
 
         public Simulation()
         {
+            this.allParts = new List<PartSim>();
+            this.allFuelLines = new List<PartSim>();
+            this.drainingParts = new HashSet<PartSim>();
+            this.allEngines = new List<EngineSim>();
+            this.activeEngines = new List<EngineSim>();
+            this.drainingResources = new HashSet<int>();
+            this.totalStageThrustForce = new ForceAccumulator();
+
+            // A dictionary for fast lookup of Part->PartSim during the preparation phase
+            partSimLookup = new Dictionary<Part, PartSim>();
+
             if (SimManager.logOutput)
             {
                 MonoBehaviour.print("Simulation created");
@@ -85,8 +99,9 @@
             {
                 double mass = 0d;
 
-                foreach (PartSim partSim in this.allParts)
-                {
+                for (int i = 0; i < this.allParts.Count; i++)
+                {
+                    PartSim partSim = this.allParts[i];
                     mass += partSim.GetMass();
                 }
 
@@ -100,8 +115,9 @@
             {
                 WeightedVectorAverager averager = new WeightedVectorAverager();
 
-                foreach (PartSim partSim in this.allParts)
-                {
+                for (int i = 0; i < this.allParts.Count; i++)
+                {
+                    PartSim partSim = this.allParts[i];
                     averager.Add(partSim.centerOfMass, partSim.GetMass());
                 }
 
@@ -132,27 +148,28 @@
             this.lastStage = Staging.lastStage;
             //MonoBehaviour.print("lastStage = " + lastStage);
 
-            // Create the lists for our simulation parts
-            this.allParts = new List<PartSim>();
-            this.allFuelLines = new List<PartSim>();
-            this.drainingParts = new HashSet<PartSim>();
-            this.allEngines = new List<EngineSim>();
-            this.activeEngines = new List<EngineSim>();
-            this.drainingResources = new HashSet<int>();
+            // Clear the lists for our simulation parts
+            this.allParts.Clear();
+            this.allFuelLines.Clear();
+            this.drainingParts.Clear();
+            this.allEngines.Clear();
+            this.activeEngines.Clear();
+            this.drainingResources.Clear();
 
             // A dictionary for fast lookup of Part->PartSim during the preparation phase
-            Dictionary<Part, PartSim> partSimLookup = new Dictionary<Part, PartSim>();
+            partSimLookup.Clear();
 
             if (this.partList.Count > 0 && this.partList[0].vessel != null)
             {
                 this.vesselName = this.partList[0].vessel.vesselName;
                 this.vesselType = this.partList[0].vessel.vesselType;
             }
-
+            //MonoBehaviour.print("PrepareSimulation pool size = " + PartSim.pool.Count());
             // First we create a PartSim for each Part (giving each a unique id)
             int partId = 1;
-            foreach (Part part in this.partList)
-            {
+            for (int i = 0; i < this.partList.Count; i++)
+            {
+                Part part = this.partList[i];
                 // If the part is already in the lookup dictionary then log it and skip to the next part
                 if (partSimLookup.ContainsKey(part))
                 {
@@ -164,7 +181,8 @@
                 }
 
                 // Create the PartSim
-                PartSim partSim = new PartSim(part, partId, this.atmosphere, log);
+                PartSim partSim = PartSim.pool.Borrow();
+                partSim.Set(part, partId, this.atmosphere, log);
 
                 // Add it to the Part lookup dictionary and the necessary lists
                 partSimLookup.Add(part, partSim);
@@ -185,16 +203,18 @@
 
             // Now that all the PartSims have been created we can do any set up that needs access to other parts
             // First we set up all the parent links
-            foreach (PartSim partSim in this.allParts)
-            {
+            for (int i = 0; i < this.allParts.Count; i++)
+            {
+                PartSim partSim = this.allParts[i];
                 partSim.SetupParent(partSimLookup, log);
             }
 
             // Then, in the VAB/SPH, we add the parent of each fuel line to the fuelTargets list of their targets
             if (HighLogic.LoadedSceneIsEditor)
             {
-                foreach (PartSim partSim in this.allFuelLines)
-                {
+                for (int i = 0; i < this.allFuelLines.Count; i++)
+                {
+                    PartSim partSim = this.allFuelLines[i];
                     CModuleFuelLine fuelLine = partSim.part.GetModule<CModuleFuelLine>();
                     if (fuelLine.target != null)
                     {
@@ -227,8 +247,9 @@
             }
 
             //MonoBehaviour.print("SetupAttachNodes and count stages");
-            foreach (PartSim partSim in this.allParts)
-            {
+            for (int i = 0; i < this.allParts.Count; i++)
+            {
+                PartSim partSim = this.allParts[i];
                 partSim.SetupAttachNodes(partSimLookup, log);
                 if (partSim.decoupledInStage >= this.lastStage)
                 {
@@ -238,8 +259,9 @@
 
             // And finally release the Part references from all the PartSims
             //MonoBehaviour.print("ReleaseParts");
-            foreach (PartSim partSim in this.allParts)
-            {
+            for (int i = 0; i < this.allParts.Count; i++)
+            {
+                PartSim partSim = this.allParts[i];
                 partSim.ReleasePart();
             }
 
@@ -260,7 +282,7 @@
 
             return true;
         }
-
+        
         // This function runs the simulation and returns a newly created array of Stage objects
         public Stage[] RunSimulation()
         {
@@ -280,13 +302,13 @@
             // Start with the last stage to simulate
             // (this is in a member variable so it can be accessed by AllowedToStage and ActivateStage)
             this.currentStage = this.lastStage;
-
             // Work out which engines would be active if just doing the staging and if this is different to the 
             // currently active engines then generate an extra stage
             // Loop through all the engines
             bool anyActive = false;
-            foreach (EngineSim engine in this.allEngines)
-            {
+            for (int i = 0; i < this.allEngines.Count; i++)
+            {
+                EngineSim engine = this.allEngines[i];
                 if (log != null)
                 {
                     log.buf.AppendLine("Testing engine mod of " + engine.partSim.name + ":" + engine.partSim.partId);
@@ -341,7 +363,7 @@
             }
 
             // Create a list of lists of PartSims that prevent decoupling
-            List<List<PartSim>> dontStagePartsLists = this.BuildDontStageLists(log);
+            this.BuildDontStageLists(log);
 
             if (log != null)
             {
@@ -350,7 +372,6 @@
 
             // Create the array of stages that will be returned
             Stage[] stages = new Stage[this.currentStage + 1];
-
 
             // Loop through the stages
             while (this.currentStage >= 0)
@@ -414,8 +435,9 @@
 
                 // Calculate the cost and mass of this stage and add all engines and tanks that are decoupled
                 // in the next stage to the dontStageParts list
-                foreach (PartSim partSim in this.allParts)
-                {
+                for (int i = 0; i < this.allParts.Count; i++)
+                {
+                    PartSim partSim = this.allParts[i];
                     if (partSim.decoupledInStage == this.currentStage - 1)
                     {
                         stage.cost += partSim.cost;
@@ -432,8 +454,9 @@
                     if (this.dontStageParts.Count > 0)
                     {
                         log.buf.AppendLine("Parts preventing staging:");
-                        foreach (PartSim partSim in this.dontStageParts)
-                        {
+                        for (int i = 0; i < this.dontStageParts.Count; i++)
+                        {
+                            PartSim partSim = this.dontStageParts[i];
                             partSim.DumpPartToBuffer(log.buf, "");
                         }
                     }
@@ -444,6 +467,7 @@
 
                     log.Flush();
                 }
+
 
                 // Now we will loop until we are allowed to stage
                 int loopCounter = 0;
@@ -451,7 +475,6 @@
                 {
                     loopCounter++;
                     //MonoBehaviour.print("loop = " + loopCounter);
-
                     // Calculate how long each draining tank will take to drain and run for the minimum time
                     double resourceDrainTime = double.MaxValue;
                     PartSim partMinDrain = null;
@@ -469,7 +492,6 @@
                     {
                         MonoBehaviour.print("Drain time = " + resourceDrainTime + " (" + partMinDrain.name + ":" + partMinDrain.partId + ")");
                     }
-
                     foreach (PartSim partSim in this.drainingParts)
                     {
                         partSim.DrainResources(resourceDrainTime);
@@ -501,7 +523,7 @@
 
                     // Recalculate the current thrust and isp for the next step
                     this.CalculateThrustAndISP();
-
+                    
                     // Check if we actually changed anything
                     if (this.stepStartMass == this.stepEndMass)
                     {
@@ -527,6 +549,7 @@
                     this.stepStartMass = this.stepEndMass;
                 }
 
+
                 // Store more values in the Stage object and stick it in the array
 
                 // Store the magnitude of the deltaV vector
@@ -606,29 +629,54 @@
                 this._timer.Stop();
                 MonoBehaviour.print("RunSimulation: " + this._timer.ElapsedMilliseconds + "ms");
             }
-
+            FreePooledObject();
+            
             return stages;
         }
 
-        private List<List<PartSim>> BuildDontStageLists(LogMsg log)
+        
+        // Make sure we free them all, even if they should all be free already at this point
+        public void FreePooledObject()
+        {
+            //MonoBehaviour.print("FreePooledObject pool size before = " + PartSim.pool.Count() + " for " + allParts.Count + " parts");
+            foreach (PartSim part in allParts)
+            {
+                PartSim.pool.Release(part);
+            }
+            //MonoBehaviour.print("FreePooledObject pool size after = " + PartSim.pool.Count());
+
+            //MonoBehaviour.print("FreePooledObject pool size before = " + EngineSim.pool.Count() + " for " + allEngines.Count + " engines");
+            foreach (EngineSim engine in allEngines)
+            {
+                EngineSim.pool.Release(engine);
+            }
+            //MonoBehaviour.print("FreePooledObject pool size after = " + EngineSim.pool.Count());
+        }
+
+        private void BuildDontStageLists(LogMsg log)
         {
             if (log != null)
             {
                 log.buf.AppendLine("Creating list with capacity of " + (this.currentStage + 1));
             }
-            List<List<PartSim>> lists = new List<List<PartSim>>();
+            
             for (int i = 0; i <= this.currentStage; i++)
             {
-                lists.Add(new List<PartSim>());
-            }
-
-            foreach (PartSim partSim in this.allParts)
-            {
+                if (i < dontStagePartsLists.Count)
+                    dontStagePartsLists[i].Clear();
+                else
+                    dontStagePartsLists.Add(new List<PartSim>());
+            }
+
+            for (int i = 0; i < this.allParts.Count; i++)
+            {
+                PartSim partSim = this.allParts[i];
                 if (partSim.isEngine || !partSim.Resources.Empty)
                 {
                     if (log != null)
                     {
-                        log.buf.AppendLine(partSim.name + ":" + partSim.partId + " is engine or tank, decoupled = " + partSim.decoupledInStage);
+                        log.buf.AppendLine(
+                            partSim.name + ":" + partSim.partId + " is engine or tank, decoupled = " + partSim.decoupledInStage);
                     }
 
                     if (partSim.decoupledInStage < -1 || partSim.decoupledInStage > this.currentStage - 1)
@@ -640,28 +688,27 @@
                     }
                     else
                     {
-                        lists[partSim.decoupledInStage + 1].Add(partSim);
+                        dontStagePartsLists[partSim.decoupledInStage + 1].Add(partSim);
                     }
                 }
             }
 
             for (int i = 1; i <= this.lastStage; i++)
             {
-                if (lists[i].Count == 0)
-                {
-                    lists[i] = lists[i - 1];
-                }
-            }
-
-            return lists;
+                if (dontStagePartsLists[i].Count == 0)
+                {
+                    dontStagePartsLists[i] = dontStagePartsLists[i - 1];
+                }
+            }
         }
 
         // This function simply rebuilds the active engines by testing the isActive flag of all the engines
         private void UpdateActiveEngines()
         {
             this.activeEngines.Clear();
-            foreach (EngineSim engine in this.allEngines)
-            {
+            for (int i = 0; i < this.allEngines.Count; i++)
+            {
+                EngineSim engine = this.allEngines[i];
                 if (engine.isActive)
                 {
                     this.activeEngines.Add(engine);
@@ -679,12 +726,12 @@
             this.totalStageActualThrust = 0d;
             this.totalStageFlowRate = 0d;
             this.totalStageIspFlowRate = 0d;
-            this.totalStageThrustForce = new ForceAccumulator();
-
+            this.totalStageThrustForce.Reset();
             // Loop through all the active engines totalling the thrust, actual thrust and mass flow rates
             // The thrust is totalled as vectors
-            foreach (EngineSim engine in this.activeEngines)
-            {
+            for (int i = 0; i < this.activeEngines.Count; i++)
+            {
+                EngineSim engine = this.activeEngines[i];
                 this.simpleTotalThrust += engine.thrust;
                 this.vecThrust += ((float)engine.thrust * engine.thrustVec);
                 this.vecActualThrust += ((float)engine.actualThrust * engine.thrustVec);
@@ -692,13 +739,13 @@
                 this.totalStageFlowRate += engine.ResourceConsumptions.Mass;
                 this.totalStageIspFlowRate += engine.ResourceConsumptions.Mass * engine.isp;
 
-                foreach (AppliedForce f in engine.appliedForces) {
+                for (int j = 0; j < engine.appliedForces.Count; j++)
+                {
+                    AppliedForce f = engine.appliedForces[j];
                     this.totalStageThrustForce.AddForce(f);
                 }
             }
-
             //MonoBehaviour.print("vecThrust = " + vecThrust.ToString() + "   magnitude = " + vecThrust.magnitude);
-
             this.totalStageThrust = this.vecThrust.magnitude;
             this.totalStageActualThrust = this.vecActualThrust.magnitude;
 
@@ -733,14 +780,16 @@
             this.drainingParts.Clear();
 
             // Loop through all the active engine modules
-            foreach (EngineSim engine in this.activeEngines)
-            {
+            for (int i = 0; i < this.activeEngines.Count; i++)
+            {
+                EngineSim engine = this.activeEngines[i];
                 // Set the resource drains for this engine
                 if (engine.SetResourceDrains(this.allParts, this.allFuelLines, this.drainingParts))
                 {
                     // If it is active then add the consumed resource types to the set
-                    foreach (int type in engine.ResourceConsumptions.Types)
-                    {
+                    for (int j = 0; j < engine.ResourceConsumptions.Types.Count; j++)
+                    {
+                        int type = engine.ResourceConsumptions.Types[j];
                         this.drainingResources.Add(type);
                     }
                 }
@@ -754,8 +803,9 @@
                 StringBuilder buffer = new StringBuilder(1024);
                 buffer.AppendFormat("Active engines = {0:d}\n", this.activeEngines.Count);
                 int i = 0;
-                foreach (EngineSim engine in this.activeEngines)
-                {
+                for (int j = 0; j < this.activeEngines.Count; j++)
+                {
+                    EngineSim engine = this.activeEngines[j];
                     engine.DumpEngineToBuffer(buffer, "Engine " + (i++) + ":");
                 }
                 MonoBehaviour.print(buffer);
@@ -775,8 +825,9 @@
 
             if (this.activeEngines.Count > 0)
             {
-                foreach (PartSim partSim in this.dontStageParts)
-                {
+                for (int i = 0; i < this.dontStageParts.Count; i++)
+                {
+                    PartSim partSim = this.dontStageParts[i];
                     if (SimManager.logOutput)
                     {
                         partSim.DumpPartToBuffer(buffer, "Testing: ");
@@ -795,8 +846,9 @@
 
                     if (partSim.isEngine)
                     {
-                        foreach (EngineSim engine in this.activeEngines)
-                        {
+                        for (int j = 0; j < this.activeEngines.Count; j++)
+                        {
+                            EngineSim engine = this.activeEngines[j];
                             if (engine.partSim == partSim)
                             {
                                 if (SimManager.logOutput)
@@ -834,9 +886,10 @@
         private void ActivateStage()
         {
             // Build a set of all the parts that will be decoupled
-            HashSet<PartSim> decoupledParts = new HashSet<PartSim>();
-            foreach (PartSim partSim in this.allParts)
-            {
+            decoupledParts.Clear();
+            for (int i = 0; i < this.allParts.Count; i++)
+            {
+                PartSim partSim = this.allParts[i];
                 if (partSim.decoupledInStage >= this.currentStage)
                 {
                     decoupledParts.Add(partSim);
@@ -847,14 +900,17 @@
             {
                 // Remove it from the all parts list
                 this.allParts.Remove(partSim);
+                PartSim.pool.Release(partSim);
                 if (partSim.isEngine)
                 {
                     // If it is an engine then loop through all the engine modules and remove all the ones from this engine part
                     for (int i = this.allEngines.Count - 1; i >= 0; i--)
                     {
-                        if (this.allEngines[i].partSim == partSim)
+                        EngineSim engine = this.allEngines[i];
+                        if (engine.partSim == partSim)
                         {
                             this.allEngines.RemoveAt(i);
+                            EngineSim.pool.Release(engine);
                         }
                     }
                 }
@@ -866,15 +922,17 @@
             }
 
             // Loop through all the (remaining) parts
-            foreach (PartSim partSim in this.allParts)
-            {
+            for (int i = 0; i < this.allParts.Count; i++)
+            {
+                PartSim partSim = this.allParts[i];
                 // Ask the part to remove all the parts that are decoupled
                 partSim.RemoveAttachedParts(decoupledParts);
             }
 
             // Now we loop through all the engines and activate those that are ignited in this stage
-            foreach (EngineSim engine in this.allEngines)
-            {
+            for (int i = 0; i < this.allEngines.Count; i++)
+            {
+                EngineSim engine = this.allEngines[i];
                 if (engine.partSim.inverseStage == this.currentStage)
                 {
                     engine.isActive = true;

 Binary files a/Output/KerbalEngineer/KerbalEngineer.dll and b/Output/KerbalEngineer/KerbalEngineer.dll differ