Avoid duplicate call to PSystemSetup.SetActive in FlightDriver.setStartupNewVessel

GameData/KSPCommunityFixes/Settings.cfg

@@ -340,6 +340,9 @@ KSP_COMMUNITY_FIXES
   // and on other occasions, wasting a ton of CPU processing time.
   PQSCoroutineLeak = true
 
+  /// Prevent KSP from restarting PQS for the current planet multiple times when launching a new ship.
+  PQSOnlyStartOnce = true
+
   // Remove unused ProgressTracking update handlers. Provides a very noticeable performance uplift in 
   // career games having a large amount of celestial bodies and/or vessels.
   ProgressTrackingSpeedBoost = true

KSPCommunityFixes/KSPCommunityFixes.csproj

@@ -221,6 +221,7 @@
     <Compile Include="Performance\ModuleDockingNodeFindOtherNodesFaster.cs" />
     <Compile Include="Performance\OptimizedModuleRaycasts.cs" />
     <Compile Include="Performance\PQSCoroutineLeak.cs" />
+    <Compile Include="Performance\PQSOnlyStartOnce.cs" />
     <Compile Include="Performance\PQSUpdateNoMemoryAlloc.cs" />
     <Compile Include="Performance\ProgressTrackingSpeedBoost.cs" />
     <Compile Include="QoL\AutostrutActions.cs" />

KSPCommunityFixes/Performance/PQSOnlyStartOnce.cs

@@ -0,0 +1,70 @@
+
+using System.Collections.Generic;
+using System.Reflection.Emit;
+using HarmonyLib;
+
+namespace KSPCommunityFixes.Performance
+{
+    class PQSOnlyStartOnce : BasePatch
+    {
+
+        protected override void ApplyPatches()
+        {
+            AddPatch(PatchType.Transpiler, typeof(FlightDriver), nameof(FlightDriver.setStartupNewVessel));
+        }
+
+
+        static IEnumerable<CodeInstruction> FlightDriver_setStartupNewVessel_Transpiler(IEnumerable<CodeInstruction> instructions, ILGenerator gen)
+        {
+            var method1 = SymbolExtensions.GetMethodInfo<PSystemSetup>(p => p.SetPQSActive(null));
+            var method2 = SymbolExtensions.GetMethodInfo<PSystemSetup>(p => p.SetPQSActive());
+
+            var matcher = new CodeMatcher(instructions);
+            var state = gen.DeclareLocal(typeof(State));
+
+            matcher
+                .MatchStartForward(new CodeMatch(OpCodes.Callvirt, method1))
+                .Repeat(
+                    matcher =>
+                    {
+                        matcher.RemoveInstruction();
+                        matcher.InsertAndAdvance(new CodeInstruction(OpCodes.Ldloca, state));
+                        matcher.InsertAndAdvance(CodeInstruction.Call<State>(s => SetPQSActive(null, null, ref s)));
+                    }
+                );
+
+            matcher.Start();
+            matcher
+                .MatchStartForward(new CodeMatch(OpCodes.Callvirt, method2))
+                .Repeat(
+                    matcher =>
+                    {
+                        matcher.RemoveInstruction();
+                        matcher.InsertAndAdvance(new CodeInstruction(OpCodes.Ldloca, state));
+                        matcher.InsertAndAdvance(CodeInstruction.Call<State>(s => SetPQSActive(null, ref s)));
+                    }
+                );
+
+            return matcher.Instructions();
+        }
+
+        struct State
+        {
+            public bool activated;
+        }
+
+        static void SetPQSActive(PSystemSetup psystem, PQS pqs, ref State state)
+        {
+            psystem.SetPQSActive(pqs);
+            state.activated = true;
+        }
+
+        static void SetPQSActive(PSystemSetup psystem, ref State state)
+        {
+            if (state.activated)
+                return;
+
+            psystem.SetPQSActive();
+        }
+    }
+}