However, I was able to increase performance a lot more by installing the Warp3D 3.1 libraries over the 4.0 libraries. Apparently Warp3D 3.1 is a bit faster than 4.0. (and 4.2 aswell, but that one is bugged, too!)
This is very insteresting. I would have give v3.1 a try, but i remember that it gives rendering problems with some games like Heretic 2. It draws black rectangles around light sources, etc.
For improving speed, i recommend to minimize the number of particles in the config file.
As for BlitzQuake, do a search in this forum and you'll see.