Improve delay between load complete and game starting

OpenRA.Game/Game.cs

@@ -223,6 +223,10 @@ internal static void StartGame(string mapUID, WorldType type)
 			//   Much better to clean up now then to drop frames during gameplay for GC pauses.
 			GCSettings.LargeObjectHeapCompactionMode = GCLargeObjectHeapCompactionMode.CompactOnce;
 			GC.Collect();
+
+			// PostLoadComplete is designed for anything that should trigger at the very end of loading.
+			// e.g. audio notifications that the game is starting.
+			OrderManager.World.PostLoadComplete(worldRenderer);
 		}
 
 		public static void RestartGame()
@@ -602,7 +606,10 @@ static void InnerLogicTick(OrderManager orderManager)
 
 			if (orderManager.LastTickTime.ShouldAdvance(tick))
 			{
-				using (new PerfSample("tick_time"))
+				if (orderManager.GameStarted && orderManager.LocalFrameNumber == 0)
+					PerfHistory.Reset(); // Remove history that occurred whilst the new game was loading.
+
+				using (var sample = new PerfSample("tick_time"))
 				{
 					orderManager.LastTickTime.AdvanceTickTime(tick);
 
@@ -611,7 +618,11 @@ static void InnerLogicTick(OrderManager orderManager)
 					Sync.RunUnsynced(world, orderManager.TickImmediate);
 
 					if (world == null)
+					{
+						if (orderManager.GameStarted)
+							PerfHistory.Reset(); // Remove old history when a new game starts.
 						return;
+					}
 
 					if (orderManager.TryTick())
 					{

OpenRA.Game/Support/PerfHistory.cs

@@ -47,5 +47,11 @@ public static void Tick()
 				if (item.HasNormalTick)
 					item.Tick();
 		}
+
+		public static void Reset()
+		{
+			foreach (var item in Items.Values)
+				item.ResetSamples();
+		}
 	}
 }

OpenRA.Game/Support/PerfItem.cs

@@ -72,5 +72,12 @@ public double LastValue
 				return samples[n];
 			}
 		}
+
+		public void ResetSamples()
+		{
+			head = 1;
+			tail = 0;
+			Val = 0.0;
+		}
 	}
 }

OpenRA.Game/Traits/TraitsInterfaces.cs

@@ -366,6 +366,7 @@ public interface INotifySelected { void Selected(Actor self); }
 	public interface INotifySelection { void SelectionChanged(); }
 
 	public interface IWorldLoaded { void WorldLoaded(World w, WorldRenderer wr); }
+	public interface IPostWorldLoaded { void PostWorldLoaded(World w, WorldRenderer wr); }
 	public interface INotifyGameLoading { void GameLoading(World w); }
 	public interface INotifyGameLoaded { void GameLoaded(World w); }
 	public interface INotifyGameSaved { void GameSaved(World w); }

OpenRA.Game/World.cs

@@ -296,16 +296,29 @@ public void LoadComplete(WorldRenderer wr)
 					using (new PerfTimer(iwl.GetType().Name + ".WorldLoaded"))
 						iwl.WorldLoaded(this, wr);
 
-			gameInfo.StartTimeUtc = DateTime.UtcNow;
 			foreach (var player in Players)
 				gameInfo.AddPlayer(player, OrderManager.LobbyInfo);
 
 			gameInfo.DisabledSpawnPoints = OrderManager.LobbyInfo.DisabledSpawnPoints;
 
+			gameInfo.StartTimeUtc = DateTime.UtcNow;
+
 			if (OrderManager.Connection is NetworkConnection nc && nc.Recorder != null)
 				nc.Recorder.Metadata = new ReplayMetadata(gameInfo);
 		}
 
+		public void PostLoadComplete(WorldRenderer wr)
+		{
+			foreach (var iwl in WorldActor.TraitsImplementing<IPostWorldLoaded>())
+				using (new PerfTimer(iwl.GetType().Name + ".PostWorldLoaded"))
+					iwl.PostWorldLoaded(this, wr);
+
+			foreach (var p in Players)
+				foreach (var iwl in p.PlayerActor.TraitsImplementing<IPostWorldLoaded>())
+					using (new PerfTimer(iwl.GetType().Name + ".PostWorldLoaded"))
+						iwl.PostWorldLoaded(this, wr);
+		}
+
 		public void SetWorldOwner(Player p)
 		{
 			WorldActor.Owner = p;

OpenRA.Mods.Common/Traits/World/MusicPlaylist.cs

@@ -43,7 +43,7 @@ public class MusicPlaylistInfo : TraitInfo
 		public override object Create(ActorInitializer init) { return new MusicPlaylist(init.World, this); }
 	}
 
-	public class MusicPlaylist : INotifyActorDisposing, IGameOver, IWorldLoaded, INotifyGameLoaded
+	public class MusicPlaylist : INotifyActorDisposing, IGameOver, IPostWorldLoaded, INotifyGameLoaded
 	{
 		readonly MusicPlaylistInfo info;
 		readonly World world;
@@ -98,7 +98,7 @@ public MusicPlaylist(World world, MusicPlaylistInfo info)
 			}
 		}
 
-		void IWorldLoaded.WorldLoaded(World world, WorldRenderer wr)
+		void IPostWorldLoaded.PostWorldLoaded(World world, WorldRenderer wr)
 		{
 			// Reset any bogus pre-existing state
 			Game.Sound.DisableWorldSounds = info.DisableWorldSounds;

OpenRA.Mods.Common/Traits/World/StartGameNotification.cs

@@ -38,15 +38,15 @@ sealed class StartGameNotificationInfo : TraitInfo
 		public override object Create(ActorInitializer init) { return new StartGameNotification(this); }
 	}
 
-	sealed class StartGameNotification : IWorldLoaded, INotifyGameLoaded, INotifyGameSaved
+	sealed class StartGameNotification : IPostWorldLoaded, INotifyGameLoaded, INotifyGameSaved
 	{
 		readonly StartGameNotificationInfo info;
 		public StartGameNotification(StartGameNotificationInfo info)
 		{
 			this.info = info;
 		}
 
-		void IWorldLoaded.WorldLoaded(World world, WorldRenderer wr)
+		void IPostWorldLoaded.PostWorldLoaded(World world, WorldRenderer wr)
 		{
 			if (!world.IsLoadingGameSave)
 			{