I think it is an engine bug actually. For some reason the game loads only a certain area of the map when you first load a save. But if I move the camera around the map and the game slowly loads the map into memory, or whatever it does, the game becomes much more stable. There's a lot of stuff in the CW2 map compared to TEAW for example, and the engine can't handle it. Maybe the game should be allowed to use more memory? Maybe an SSD would help?