I'm not sure but I believe the "self-shadows" are only applied to the "actively" viewed object. Even then, only within a certain distance. I don't think this is a performance hog. Modern videocards should be able to handle large numbers of vertices as well. One of the things that I found which affects performance noticeably are dynamic lights (flood lights, formation lights, position lights and taxi&landing lights). You can disable lights on your aircraft but not the AI, so when they start taking-off or come in landing ... ;) The AI sometimes turn on formation lights in the middle of the day ...