I have FINALLY nailed down the reason of 8 constant, nerve-racking 8 fps.
Its the bloody environment effects. Frostbite is IMPOSSIBLE to play, as is marshes with all the bleeding flying glow-stick insects.
Also adding to this is the missile smoke.
These two (but especially the env effects) eat CPU like theres no tomorrow. My gfx card seems to be coping, but for some reason my cpu isnt.
People with faster CPUs dont have that problem, though.
C2D E6600. (2.71ghz).