Actually uzi's script is the way to do it. Rolfy's script will CONTINUOUSLY load the "none.fx" shader, which will eventually overload the cpu and drag your framerate down to a standstill.
You only need to set the postprocessing to "none" ONCE, then move to a new state to prevent it from loading the same effect over and over again. Just use a trigger zone, a single trigger zone is all you need, or preload the effect by inserting the command in the "setuplevel.fpi" script.
SPECS: Windows7 x64, Intel Core i7 920, Geforce GTX 580, 6GB RAM