Ive just had this problem last night while playing in demo server. I was trying to AFK for awhile so, I decided to press Shift+F4 to change it to windowed mode. To my suprise, the fps dropped so much that from 50~60 to 6 fps! What actually happened? When I pressed Shift+F4 again(to change to full screen mode) the fps seems to be normal (50~60fps)..
Is it me? or my card? or my mind? or lfs.exe?
my card? had the latest driver (that runs well with my card) from ATi.com
lfs.exe? its a V-Patch.