TooltipWidgetContainer, load tooltip ui only when visible.

OpenRA.Mods.Common/Widgets/TooltipContainerWidget.cs

@@ -28,20 +28,38 @@ namespace OpenRA.Mods.Common.Widgets
 		Widget tooltip;
 		int nextToken = 1;
 		int currentToken;
+		string id;
+		WidgetArgs widgetArgs;
 
 		public TooltipContainerWidget()
 		{
 			graphicSettings = Game.Settings.Graphics;
-			IsVisible = () => Game.RunTime > Viewport.LastMoveRunTime + TooltipDelayMilliseconds;
+			IsVisible = () =>
+			{
+				// PERF: Only load widget once visible.
+				var visible = Game.RunTime > Viewport.LastMoveRunTime + TooltipDelayMilliseconds;
+				if (visible)
+					LoadWidget();
+
+				return visible;
+			};
+		}
+
+		void LoadWidget()
+		{
+			if (id == null || tooltip != null)
+				return;
+
+			tooltip = Ui.LoadWidget(id, this, new WidgetArgs(widgetArgs) { { "tooltipContainer", this } });
 		}
 
 		public int SetTooltip(string id, WidgetArgs args)
 		{
 			RemoveTooltip();
 			currentToken = nextToken++;
-
-			tooltip = Ui.LoadWidget(id, this, new WidgetArgs(args) { { "tooltipContainer", this } });
-
+			tooltip = null;
+			this.id = id;
+			widgetArgs = args;
 			return currentToken;
 		}
 
@@ -50,6 +68,10 @@ namespace OpenRA.Mods.Common.Widgets
 			if (currentToken != token)
 				return;
 
+			tooltip = null;
+			id = null;
+			widgetArgs = null;
+
 			RemoveChildren();
 			BeforeRender = Nothing;
 		}
@@ -59,7 +81,10 @@ namespace OpenRA.Mods.Common.Widgets
 			RemoveTooltip(currentToken);
 		}
 
-		public override void Draw() { BeforeRender(); }
+		public override void Draw()
+		{
+			BeforeRender();
+		}
 
 		public override bool EventBoundsContains(int2 location) { return false; }