Improve performance of name sorting in town and station list windows

src/saveload/afterload.cpp

@@ -232,6 +232,12 @@ void UpdateAllVirtCoords()
 	RebuildViewportKdtree();
 }
 
+void ClearAllCachedNames()
+{
+	ClearAllStationCachedNames();
+	ClearAllTownCachedNames();
+}
+
 /**
  * Initialization of the windows and several kinds of caches.
  * This is not done directly in AfterLoadGame because these
@@ -248,6 +254,7 @@ static void InitializeWindowsAndCaches()
 	SetupColoursAndInitialWindow();
 
 	/* Update coordinates of the signs. */
+	ClearAllCachedNames();
 	UpdateAllVirtCoords();
 	ResetViewportAfterLoadGame();