[Loren]

About Alt-Tab: Yes, it doesn't work right while the AI is thinking. It appears to me that the system doesn't relinquish the display unless it's writing something to it. It's easy to circumvent this problem, though: Run the game in a window. This avoids all the problems with control of the display because it never has control, it's merely an ordinary window that the system can deal with even if it's unresponsive.

About long thinks: I think I've figured this one out. I abandoned one game because of it and I've seen signs of it a couple of other times but it didn't get insane. The probelm seems to be LA Ermor (and this would apply to any other undead empires, I haven't played enough to know if there are others.) getting insane armies. When you have some armies with a few thousand units each stomping around the battlefield it takes the game an insane amount of time to figure out what to do with them.