I was getting terrible frame rates as well on AMD Phenom II 6 core processor overclocked to 3.1 gHz and HD 5850 graphics card. I noticed however that the game seems to be fairly CPU intensive. Perhaps there is room for optimization, game is in beta after all.
Anyway for me, a quick vacuuming of the CPU cooler, along with changing some of the settings and closing down unnecessary applications from background did the trick. I would assume that vacuuming had the biggest effect but if someone wants to try the settings I got this to work on I'll pos them:
-native reso (fullscreen)
-no AA
-texture filtering: low
-all the details on advanced page 1 on medium
-everything checked on advanced page 4
Smooth 60fps with this on 32 player game online.