3dimensions, after trying lots of configs i did something that really works, changed my viewport FTS from 5fps to 250fps in my GTX470! but there's a problem, i'll explain later... Try the following:
1 - download latest drivers form nVidia
2 - perform a clean install. Uncheck all (nVidia HiDefinnition Audio and nVidia Updates), check only the Drivers and Physx
3 - proceed with install
4 - DON'T RESTART YOUR PC
5 - Start Max
6 - Enjoy Full Speed
But when you restart your machine,, slow again. Now I have setup.exe (nvidia) in my computer's startup. I want to keep it permanent, but solves the problem for now. I'm in contact with nVidia support, i can call you if i fix it.
Hope it works for you too!!!