[kairi00]

First things first:
1. Uncheck "Full VRAM Primitives"... that totally slows everything down!!!!
2. Then lower your resolution to 640x480 *fullscreen*, and gradually bump it up.

 

[kairi00]

Like Demigod said, FSAA affects the entire screen, prerendered or not.... however, *edge* antialiasing (which was present in older DirectX) won't affect prerendered backgrounds.