So I have a... Very weird issue. I'm suffering severe FPS drops, down to 2 or 6 FPS, but those happen... Exclusively after restarting.
Let me be a bit more clear: I go and update my drivers, after that process is complete (computer doesn't restarts) the game runs very smoothly. However, if I restart for some reason (I don't tend to turn the computer off) then suddenly I get massive FPS drops nearby groups of people or when turning the camera.

I'm using a Radeon HD6800

What could be the source?