diff --git a/OpenRA.Game/Game.cs b/OpenRA.Game/Game.cs
index a9ddcffa4b..2c9eeff87c 100644
--- a/OpenRA.Game/Game.cs
+++ b/OpenRA.Game/Game.cs
@@ -40,6 +40,7 @@ namespace OpenRA
 		public static Settings Settings;
 		public static CursorManager Cursor;
 		public static bool HideCursor;
+
 		static WorldRenderer worldRenderer;
 		static string modLaunchWrapper;
 
@@ -589,7 +590,7 @@ namespace OpenRA
 			if (Ui.LastTickTime.ShouldAdvance(tick))
 			{
 				Ui.LastTickTime.AdvanceTickTime(tick);
-				Sync.RunUnsynced(Settings.Debug.SyncCheckUnsyncedCode, world, Ui.Tick);
+				Sync.RunUnsynced(world, Ui.Tick);
 				Cursor.Tick();
 			}
 
@@ -601,14 +602,14 @@ namespace OpenRA
 
 					Sound.Tick();
 
-					Sync.RunUnsynced(Settings.Debug.SyncCheckUnsyncedCode, world, orderManager.TickImmediate);
+					Sync.RunUnsynced(world, orderManager.TickImmediate);
 
 					if (world == null)
 						return;
 
 					if (orderManager.TryTick())
 					{
-						Sync.RunUnsynced(Settings.Debug.SyncCheckUnsyncedCode, world, () =>
+						Sync.RunUnsynced(world, () =>
 						{
 							world.OrderGenerator.Tick(world);
 						});
@@ -620,7 +621,7 @@ namespace OpenRA
 
 					// Wait until we have done our first world Tick before TickRendering
 					if (orderManager.LocalFrameNumber > 0)
-						Sync.RunUnsynced(Settings.Debug.SyncCheckUnsyncedCode, world, () => world.TickRender(worldRenderer));
+						Sync.RunUnsynced(world, () => world.TickRender(worldRenderer));
 				}
 
 				benchmark?.Tick(LocalTick);
diff --git a/OpenRA.Game/Input/InputHandler.cs b/OpenRA.Game/Input/InputHandler.cs
index e8c46e69eb..18d8833902 100644
--- a/OpenRA.Game/Input/InputHandler.cs
+++ b/OpenRA.Game/Input/InputHandler.cs
@@ -37,17 +37,17 @@ namespace OpenRA
 
 		public void OnKeyInput(KeyInput input)
 		{
-			Sync.RunUnsynced(Game.Settings.Debug.SyncCheckUnsyncedCode, world, () => Ui.HandleKeyPress(input));
+			Sync.RunUnsynced(world, () => Ui.HandleKeyPress(input));
 		}
 
 		public void OnTextInput(string text)
 		{
-			Sync.RunUnsynced(Game.Settings.Debug.SyncCheckUnsyncedCode, world, () => Ui.HandleTextInput(text));
+			Sync.RunUnsynced(world, () => Ui.HandleTextInput(text));
 		}
 
 		public void OnMouseInput(MouseInput input)
 		{
-			Sync.RunUnsynced(Game.Settings.Debug.SyncCheckUnsyncedCode, world, () => Ui.HandleInput(input));
+			Sync.RunUnsynced(world, () => Ui.HandleInput(input));
 		}
 	}
 
diff --git a/OpenRA.Game/Sync.cs b/OpenRA.Game/Sync.cs
index 40f3e389a1..542de78c6c 100644
--- a/OpenRA.Game/Sync.cs
+++ b/OpenRA.Game/Sync.cs
@@ -161,6 +161,11 @@ namespace OpenRA
 			return t.GetHashCode();
 		}
 
+		public static void RunUnsynced(World world, Action fn)
+		{
+			RunUnsynced(Game.Settings.Debug.SyncCheckUnsyncedCode, world, () => { fn(); return true; });
+		}
+
 		public static void RunUnsynced(bool checkSyncHash, World world, Action fn)
 		{
 			RunUnsynced(checkSyncHash, world, () => { fn(); return true; });
@@ -168,13 +173,18 @@ namespace OpenRA
 
 		static bool inUnsyncedCode = false;
 
+		public static T RunUnsynced<T>(World world, Func<T> fn)
+		{
+			return RunUnsynced(Game.Settings.Debug.SyncCheckUnsyncedCode, world, fn);
+		}
+
 		public static T RunUnsynced<T>(bool checkSyncHash, World world, Func<T> fn)
 		{
-			if (world == null)
+			// PERF: Detect sync changes in top level entry point only. Do not recalculate sync hash during reentry.
+			if (inUnsyncedCode || world == null)
 				return fn();
 
 			var sync = checkSyncHash ? world.SyncHash() : 0;
-			var prevInUnsyncedCode = inUnsyncedCode;
 			inUnsyncedCode = true;
 
 			try
@@ -183,7 +193,7 @@ namespace OpenRA
 			}
 			finally
 			{
-				inUnsyncedCode = prevInUnsyncedCode;
+				inUnsyncedCode = false;
 				if (checkSyncHash && sync != world.SyncHash())
 					throw new InvalidOperationException("RunUnsynced: sync-changing code may not run here");
 			}
diff --git a/OpenRA.Mods.Common/Traits/World/LoadWidgetAtGameStart.cs b/OpenRA.Mods.Common/Traits/World/LoadWidgetAtGameStart.cs
index b8116d1997..ed6c53fd2b 100644
--- a/OpenRA.Mods.Common/Traits/World/LoadWidgetAtGameStart.cs
+++ b/OpenRA.Mods.Common/Traits/World/LoadWidgetAtGameStart.cs
@@ -85,7 +85,7 @@ namespace OpenRA.Mods.Common.Traits
 				var optionsButton = root.GetOrNull<MenuButtonWidget>("OPTIONS_BUTTON");
 				world.SetPauseState(false);
 				if (optionsButton != null)
-					Sync.RunUnsynced(Game.Settings.Debug.SyncCheckUnsyncedCode, world, optionsButton.OnClick);
+					Sync.RunUnsynced(world, optionsButton.OnClick);
 			}
 		}
 	}
diff --git a/OpenRA.Mods.Common/Traits/World/Selection.cs b/OpenRA.Mods.Common/Traits/World/Selection.cs
index 4c9f9573a7..b048fa054b 100644
--- a/OpenRA.Mods.Common/Traits/World/Selection.cs
+++ b/OpenRA.Mods.Common/Traits/World/Selection.cs
@@ -56,7 +56,7 @@ namespace OpenRA.Mods.Common.Traits
 			foreach (var sel in a.TraitsImplementing<INotifySelected>())
 				sel.Selected(a);
 
-			Sync.RunUnsynced(Game.Settings.Debug.SyncCheckUnsyncedCode, world, () => world.OrderGenerator.SelectionChanged(world, actors));
+			Sync.RunUnsynced(world, () => world.OrderGenerator.SelectionChanged(world, actors));
 			foreach (var ns in worldNotifySelection)
 				ns.SelectionChanged();
 		}
@@ -66,7 +66,7 @@ namespace OpenRA.Mods.Common.Traits
 			if (actors.Remove(a))
 			{
 				UpdateHash();
-				Sync.RunUnsynced(Game.Settings.Debug.SyncCheckUnsyncedCode, world, () => world.OrderGenerator.SelectionChanged(world, actors));
+				Sync.RunUnsynced(world, () => world.OrderGenerator.SelectionChanged(world, actors));
 				foreach (var ns in worldNotifySelection)
 					ns.SelectionChanged();
 			}
@@ -121,7 +121,7 @@ namespace OpenRA.Mods.Common.Traits
 				foreach (var sel in a.TraitsImplementing<INotifySelected>())
 					sel.Selected(a);
 
-			Sync.RunUnsynced(Game.Settings.Debug.SyncCheckUnsyncedCode, world, () => world.OrderGenerator.SelectionChanged(world, actors));
+			Sync.RunUnsynced(world, () => world.OrderGenerator.SelectionChanged(world, actors));
 			foreach (var ns in worldNotifySelection)
 				ns.SelectionChanged();
 
@@ -148,7 +148,7 @@ namespace OpenRA.Mods.Common.Traits
 		{
 			actors.Clear();
 			UpdateHash();
-			Sync.RunUnsynced(Game.Settings.Debug.SyncCheckUnsyncedCode, world, () => world.OrderGenerator.SelectionChanged(world, actors));
+			Sync.RunUnsynced(world, () => world.OrderGenerator.SelectionChanged(world, actors));
 			foreach (var ns in worldNotifySelection)
 				ns.SelectionChanged();
 		}
@@ -170,7 +170,7 @@ namespace OpenRA.Mods.Common.Traits
 			if (removed > 0)
 			{
 				UpdateHash();
-				Sync.RunUnsynced(Game.Settings.Debug.SyncCheckUnsyncedCode, world, () => world.OrderGenerator.SelectionChanged(world, actors));
+				Sync.RunUnsynced(world, () => world.OrderGenerator.SelectionChanged(world, actors));
 				foreach (var ns in worldNotifySelection)
 					ns.SelectionChanged();
 			}
diff --git a/OpenRA.Mods.Common/Widgets/Logic/Ingame/LoadIngamePlayerOrObserverUILogic.cs b/OpenRA.Mods.Common/Widgets/Logic/Ingame/LoadIngamePlayerOrObserverUILogic.cs
index 3c2e50b630..f8a638ae56 100644
--- a/OpenRA.Mods.Common/Widgets/Logic/Ingame/LoadIngamePlayerOrObserverUILogic.cs
+++ b/OpenRA.Mods.Common/Widgets/Logic/Ingame/LoadIngamePlayerOrObserverUILogic.cs
@@ -74,7 +74,7 @@ namespace OpenRA.Mods.Common.Widgets.Logic
 
 				var optionsButton = playerRoot.GetOrNull<MenuButtonWidget>("OPTIONS_BUTTON");
 				if (optionsButton != null)
-					Sync.RunUnsynced(Game.Settings.Debug.SyncCheckUnsyncedCode, world, optionsButton.OnClick);
+					Sync.RunUnsynced(world, optionsButton.OnClick);
 			};
 		}
 	}
diff --git a/OpenRA.Mods.Common/Widgets/WorldInteractionControllerWidget.cs b/OpenRA.Mods.Common/Widgets/WorldInteractionControllerWidget.cs
index 8e1375cb95..4e7110dc26 100644
--- a/OpenRA.Mods.Common/Widgets/WorldInteractionControllerWidget.cs
+++ b/OpenRA.Mods.Common/Widgets/WorldInteractionControllerWidget.cs
@@ -211,7 +211,7 @@ namespace OpenRA.Mods.Common.Widgets
 
 		public override string GetCursor(int2 screenPos)
 		{
-			return Sync.RunUnsynced(Game.Settings.Debug.SyncCheckUnsyncedCode, World, () =>
+			return Sync.RunUnsynced(World, () =>
 			{
 				// Always show an arrow while selecting
 				if (IsValidDragbox)