Thanks alot for your helpful replies! I've added the recommended reg keys and set VideoMemorySize to 1024, used xosd to monitor my fps. When standing still, I get 10 fps, and when turning I get 0-1 fps. Disabling reflections (or lowering any of the other options) don't seem to influence the fps. The only reg key I can't add is the UseGLSL=disabled, because my game won't start then. Maybe ATI doesn't play nice with GW2..
