Go into your doomconfig.cfg file in your Base folder, and change the setting "seta image_cacheMegs" to the amount of RAM you have in your system, 512, 1024, however much it is... it seems to make a nice difference. It's worked on my 9700pro and on my room mates GF4-TI4200.
Give it a try... post back if it works... I got this off of Guru3d.
Give it a try... post back if it works... I got this off of Guru3d.