Low FPS problems, stutter

First off, system specs:

i5 2500k @ 3.3GHz (stock) w/ Cooler Master Hyper 212 CPU Fan
ATI 6850
8gb ram

Let me start off by saying that in Phase 3 Beta I had great FPS. I set the game to max settings but turned down a few settings and was at a steady 50-60 fps. Now at lowest settings, the highest fps in an open area without shadows or much bright light I'm lucky to get 40-50. On average when I'm in a city or anywhere where there's a lot of people I'm getting 10-25 fps. I'm running it in 1980

I have no idea if this game is cpu or gpu heavy, or how to check the usage in game to see what, if anything I need to upgrade. I feel that these FPS are unacceptable with the hardware, especially compared with my phase 3 FPS.

Any help would be greatly appreciated