I haven't seen this mentioned here, but going from full screen to windowed mode (alt-enter) made a huge jump in FPS for me (from 13-15 to 25+) for the same scenario. I wanted to enable windowed mode so I could see the task manager CPU performance load. CPU 1 was at about 80% and CPU 2 hovered between 40 and 80%.Anyone else see any performance difference between Full Screen and Windowed?My rig-Pentium 'D' 3.2GHz dual-core, 3GB DDR2, ATI X850XT, 19" LCD @1280x1024, 2x250GB SATA in RAID0, Intel 955 motherboard.- Tim

Just taking a shot here, but I "believe" that the reason you're seeing the jump is the difference in resolution. When you go to window'd mode the resolution jumps to your desktop resolution. So if you are running full screen at a higher resolution than your desktop, it would make sense that you would see a performance increase in a window. You could try an experiment and change the resolution in FS to that of your desktop and check out both again. It won't look as good full screen but the frames will probably be about the same as in a window.Dave