I did try everything in the options actually to be honest, with no difference.
I was surprised at first to see how smooth the 3D objects were, then I saw the performance drop. FSAA was disabled. I did try to enable it to see any difference. Same (low) performances, same (great) smooth edges. I'm very sensitive to antialiasing and I can say for sure it's always on for me.
The brightness problem on the other hand seems to touch only *some* games, not all (Tekken 3 is too bright in 3D rendering for example. 2D menus are good.).