For me performance pretty much remains the same. If I choose a higher resolution and turn on AA/AF, it obviously becomes worse.
But overall I am very satisfied with the performance. I run the game 1280x1024 with 4xAA and 8xAF, and most effects switched on on my P4 3.4, 1.5 GByte RAM, 512 MB Geforce 7800 GT.
Performance from external view is about 20-28 fps, inside 45-50.
