For rFactor, I used NVidia Inspector to change the compatibility bit, from the default Dragon Age 2 to Need For Speed: Shift. Ambient Occlusion really is a resource hungry stuff. In rF1, the FPS while sitting in a car in the garage is ~240 (with AO off). After getting AO to work, the FPS drop to 140. And when I'm driving the car with no AI, the FPS drop further to 60-75 around the track. Driving with one AI in front of me, FPS drops again to 20-30. Viewing the race from track side cameras, the FPS hit the lowest 12. I set the AO setting to Quality mode by the way. In short, AO is able to give more depth to objects. But in rF1 I can't see any difference in terms of image quality between AO on and AO off. >.< I'm going to try the AO with rF2, maybe this time I can see the difference.
