Calculate maxTransmitDistance during OnLoad to avoid the Sqrt every time it's called.
Calculate maxTransmitDistance during OnLoad to avoid the Sqrt every time it's called.

--- a/ARFlightController.cs
+++ b/ARFlightController.cs
@@ -2,7 +2,7 @@
 //
 // ARFlightController.cs
 //
-// Copyright © 2014, toadicus
+// Copyright © 2014-2015, toadicus
 // All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without modification,
@@ -224,7 +224,7 @@
 
 		private void Update()
 		{
-			if (!this.updateTimer.IsRunning || this.updateTimer.ElapsedMilliseconds > 83L)
+			if (!this.updateTimer.IsRunning || this.updateTimer.ElapsedMilliseconds > 16L)
 			{
 				this.updateTimer.Restart();
 			}

--- a/ARMapRenderer.cs
+++ b/ARMapRenderer.cs
@@ -2,7 +2,7 @@
 //
 // ARMapRenderer.cs
 //
-// Copyright © 2014, toadicus
+// Copyright © 2014-2015, toadicus
 // All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without modification,

--- a/AntennaRelay.cs
+++ b/AntennaRelay.cs
@@ -2,7 +2,7 @@
 //
 // AntennaRelay.cs
 //
-// Copyright © 2014, toadicus
+// Copyright © 2014-2015, toadicus
 // All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without modification,
@@ -198,6 +198,7 @@
 			this.KerbinDirect = true;
 
 			CelestialBody bodyOccludingBestOccludedRelay = null;
+			IAntennaRelay needle;
 
 			double nearestRelaySqrDistance = double.PositiveInfinity;
 			double bestOccludedSqrDistance = double.PositiveInfinity;
@@ -325,19 +326,49 @@
 
 				log.Append("\n\t\t...passed distance check");
 
-				if (
-					potentialBestRelay.CanTransmit() &&
-					(potentialBestRelay.targetRelay == null || potentialBestRelay.targetRelay.vessel != this.vessel))
-				{
-					// @TODO: Moved this here from outside the loop; why was it there?
-					nearestRelaySqrDistance = potentialSqrDistance;
-					this.nearestRelay = potentialBestRelay;
-
-					log.AppendFormat("\n\t{0}: found new nearest relay {1} ({2}m)",
-						this.ToString(),
-						this.nearestRelay.ToString(),
-						Math.Sqrt(nearestRelaySqrDistance)
-					);
+				if (potentialBestRelay.CanTransmit())
+				{
+					needle = potentialBestRelay;
+					bool isCircular = false;
+
+					while (needle != null)
+					{
+						if (needle.KerbinDirect)
+						{
+							break;
+						}
+
+						if (needle.targetRelay == null)
+						{
+							break;
+						}
+
+						if (needle.targetRelay.vessel == this.vessel || needle == this.moduleRef)
+						{
+							isCircular = true;
+							break;
+						}
+
+						needle = needle.targetRelay;
+					}
+
+					if (!isCircular)
+					{
+						nearestRelaySqrDistance = potentialSqrDistance;
+						this.nearestRelay = potentialBestRelay;
+
+						log.AppendFormat("\n\t{0}: found new nearest relay {1} ({2}m)",
+							this.ToString(),
+							this.nearestRelay.ToString(),
+							Math.Sqrt(nearestRelaySqrDistance)
+						);
+					}
+					else
+					{
+						log.AppendFormat("\n\t\t...connection to {0} would result in a circular network, skipping",
+							potentialBestRelay
+						);
+					}
 				}
 			}
 
@@ -347,6 +378,15 @@
 			kerbinSqrDistance *= kerbinSqrDistance;
 
 			log.AppendFormat("\n{0} ({1}): Search done, figuring status.", this.ToString(), this.GetType().Name);
+			log.AppendFormat(
+				"\n{0}: nearestRelay={1} ({2}m²)), bestOccludedRelay={3} ({4}m²), kerbinSqrDistance={5}m²)",
+				this,
+				this.nearestRelay == null ? "null" : this.nearestRelay.ToString(),
+				nearestRelaySqrDistance,
+				this.bestOccludedRelay == null ? "null" : this.bestOccludedRelay.ToString(),
+				bestOccludedSqrDistance,
+				kerbinSqrDistance
+			);
 
 			// If we don't have LOS to Kerbin, focus on relays
 			if (!this.vessel.hasLineOfSightTo(Kerbin, out bodyOccludingKerbin, ARConfiguration.RadiusRatio))
@@ -390,7 +430,7 @@
 							log.AppendFormat("\n\t\t\t\t...but the nearest relay is closer ({0} < {1}), so picking it.",
 								nearestRelaySqrDistance, bestOccludedSqrDistance);
 							
-							this.targetRelay = nearestRelay;
+							this.targetRelay = this.nearestRelay;
 							this.firstOccludingBody = null;
 						}
 						// Otherwise, target the best occluded relay.
@@ -420,7 +460,7 @@
 								nearestRelaySqrDistance, kerbinSqrDistance);
 							
 							this.KerbinDirect = false;
-							this.targetRelay = nearestRelay;
+							this.targetRelay = this.nearestRelay;
 						}
 						// Otherwise, pick Kerbin.
 						else
@@ -511,7 +551,7 @@
 								log.AppendFormat("\n\t\t\t\t...but the nearest relay is closer ({0} < {1}), so picking it.",
 									nearestRelaySqrDistance, bestOccludedSqrDistance);
 								
-								this.targetRelay = nearestRelay;
+								this.targetRelay = this.nearestRelay;
 								this.firstOccludingBody = null;
 							}
 							// Otherwise, target the best occluded relay.
@@ -541,7 +581,7 @@
 									nearestRelaySqrDistance, kerbinSqrDistance);
 								
 								this.KerbinDirect = false;
-								this.targetRelay = nearestRelay;
+								this.targetRelay = this.nearestRelay;
 							}
 							// Otherwise, pick Kerbin.
 							else

--- a/GameData/AntennaRange/AntennaRange.cfg
+++ b/GameData/AntennaRange/AntennaRange.cfg
@@ -2,7 +2,7 @@
 //
 // AntennaRange.cfg
 //
-// Copyright © 2014, toadicus
+// Copyright © 2014-2015, toadicus
 // All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without modification,

--- a/IAntennaRelay.cs
+++ b/IAntennaRelay.cs
@@ -2,7 +2,7 @@
 //
 // IAntennaRelay.cs
 //
-// Copyright © 2014, toadicus
+// Copyright © 2014-2015, toadicus
 // All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without modification,

--- a/ModuleLimitedDataTransmitter.cs
+++ b/ModuleLimitedDataTransmitter.cs
@@ -2,7 +2,7 @@
 //
 // ModuleLimitedDataTransmitter.cs
 //
-// Copyright © 2014, toadicus
+// Copyright © 2014-2015, toadicus
 // All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without modification,
@@ -205,11 +205,8 @@
 		/// </summary>
 		public double maxTransmitDistance
 		{
-			get
-			{
-				// TODO: Cache this in a way that doesn't break everything.
-				return Math.Sqrt(this.maxPowerFactor) * this.nominalRange;
-			}
+			get;
+			protected set;
 		}
 
 		/// <summary>
@@ -393,6 +390,8 @@
 			base.Fields.Load(node);
 
 			base.OnLoad (node);
+
+			this.maxTransmitDistance = Math.Sqrt(this.maxPowerFactor) * this.nominalRange;
 		}
 
 		/// <summary>

--- a/Properties/AssemblyInfo.cs
+++ b/Properties/AssemblyInfo.cs
@@ -2,7 +2,7 @@
 //
 // AssemblyInfo.cs
 //
-// Copyright © 2014, toadicus
+// Copyright © 2014-2015, toadicus
 // All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without modification,

--- a/ProtoAntennaRelay.cs
+++ b/ProtoAntennaRelay.cs
@@ -2,7 +2,7 @@
 //
 // ProtoAntennaRelay.cs
 //
-// Copyright © 2014, toadicus
+// Copyright © 2014-2015, toadicus
 // All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without modification,

--- a/RelayDatabase.cs
+++ b/RelayDatabase.cs
@@ -2,7 +2,7 @@
 //
 // RelayDatabase.cs
 //
-// Copyright © 2014, toadicus
+// Copyright © 2014-2015, toadicus
 // All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without modification,
@@ -37,27 +37,8 @@
 
 namespace AntennaRange
 {
-	public class RelayDatabase
+	public class RelayDatabase : Singleton<RelayDatabase>
 	{
-		/*
-		 * Static members
-		 * */
-		// Singleton storage
-		private static RelayDatabase _instance;
-		// Gets the singleton
-		public static RelayDatabase Instance
-		{
-			get
-			{	
-				if (_instance == null)
-				{
-					_instance = new RelayDatabase();
-				}
-
-				return _instance;
-			}
-		}
-
 		/*
 		 * Instance members
 		 * */
@@ -124,6 +105,15 @@
 			this.relayDatabase.Remove(vessel.id);
 			this.vesselPartCountTable.Remove(vessel.id);
 			this.bestRelayTable.Remove(vessel.id);
+		}
+
+		public void ClearCache()
+		{
+			Tools.PostLogMessage("RelayDatabase: onSceneChange clearing entire cache.");
+
+			this.relayDatabase.Clear();
+			this.bestRelayTable.Clear();
+			this.vesselPartCountTable.Clear();
 		}
 
 		// Returns true if both the relayDatabase and the vesselPartCountDB contain the vessel id.
@@ -253,13 +243,14 @@
 				}
 				else
 				{
-					Tools.PostLogMessage("RelayDatabase: onSceneChange clearing entire cache.");
-
-					this.relayDatabase.Clear();
-					this.bestRelayTable.Clear();
-					this.vesselPartCountTable.Clear();
-				}
-			}
+					this.ClearCache();
+				}
+			}
+		}
+
+		private void onGameLoaded(object data)
+		{
+			this.ClearCache();
 		}
 
 		// Runs when parts are undocked
@@ -431,6 +422,7 @@
 			GameEvents.onGameSceneLoadRequested.Add(this.onSceneChange);
 			GameEvents.onPartCouple.Add(this.onFromPartToPartEvent);
 			GameEvents.onPartUndock.Add(this.onPartEvent);
+			GameEvents.onGameStateLoad.Add(this.onGameLoaded);
 		}
 
 		~RelayDatabase()
@@ -442,6 +434,7 @@
 			GameEvents.onGameSceneLoadRequested.Remove(this.onSceneChange);
 			GameEvents.onPartCouple.Remove(this.onFromPartToPartEvent);
 			GameEvents.onPartUndock.Remove(this.onPartEvent);
+			GameEvents.onGameStateLoad.Remove(this.onGameLoaded);
 
 			Tools.PostDebugMessage(this.GetType().Name + " destroyed.");
 

--- a/RelayExtensions.cs
+++ b/RelayExtensions.cs
@@ -2,7 +2,7 @@
 //
 // Extensions.cs
 //
-// Copyright © 2014, toadicus
+// Copyright © 2014-2015, toadicus
 // All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without modification,