Game running in fullscreen windowed mode, other apps' GUIs lag

[CKent]

I run WoW in fullscreen windowed mode. It's useful when someone in my group goes afk and I have to kill a few minutes, or whatever, while somewhat keeping an eye on my screen. I find that in whatever window I tab to, the app's UI lags. For example, I tab over to foobar, try to hit play, but the cursor lags and I have to wait a few seconds for it to stop lagging so that I can hit play. Same thing with web pages, etc. I have noticed that the larger the window, the less lag. For example, my small IM and foobar windows have a lot of lag, but if I make my browser window large or fullscreen, there's no lag when I tab over to it. I just upgraded from a p4b 2.67 / gb ram / 9800 pro, running WoW in 1280x1024 which didn't have this problem at all, to my current x2 4800+ / 2gb ram / 1950xt running WOW in 1680x1050 where it's becoming really annoying. In fact, I'm playing WoW right now on a 3rd pc right now, also old, which also doesn't have this problem; a barton mobile 2000+, gb ram, g4 ti-4600 (lol, I know I know).

Why does this happen, and is there a way to alleviate it?

 

[CKent]

Update: In the bizarre and unlikely scenario someone else is having this problem or simply wondering what the problem was, I got an answer in WoW's tech support forum: It was having an antialiasing value of >1. I turned it down to 1 and the problem's gone, at a slight cost of visual quality. Apparently this is an issue with ATI cards, and upgrading to Vista would solve it (though it would cost me $500 and introduce 500 new bugs, so... no ).