Changing focus speeds things up

When I load my first flight in FS X all is very fine. The flight is usually loaded within 30 seconds or so. But if I have to load another flight after that (for instance after changing an option that requires a reload or after loading another flight) it takes AGES before FS X is done. Sometimes the progress bar is just stuck for a while. (Changing options itself can also take ages (before the clicks are accepted.) That's why I always quit FS X completely when I want to change a simple option... Because after re-starting FS X everything is fine again (well, not everything, but the first loadtime). BTW I also disabled the quit-warning because even that option could take ages to react. Now I just press ctrl-c and I'm out.Yesterday I accidently found out that when I change focus from FS X to antyhing else (desktop or whatever) the loading immediately speeds up again! So now I always alt-enter to windowed mode before I change or do ANYTHING. Whenever FS X get stuck or slow (with loading) I just click on the desktop and the progress bar starts moving again.This is in Vista Home Premium with a E6600, 2 Gb ram and a 8800GTX.Now I'm very happy I've found some sort of solution, but I really wonder what's happening here... How is this possible? Something wrong with how FS X addresses the cpu of memory...?