It depends on your settings. You can tweak so you get a zillion fps or tweak so you get 20 fps no problems.

I can easily get over 50fps if I change my Anti-aliasing and other card settings. I have most of my sliders maxed. I take some shots of urban areas utilizing Bev Scenery, Ultimate Terrain, US Landclass, and 38mm Mesh. I still hover in the 20s and 30s. I'll try to do that soon.