ROFL, I would be down for that. They should make it an option to have a "knife only" round every once in awhile.
It's your CPU. Bad Company 2 played horribly on my old E8400, ok on a Q9550, and perfectly on an i5 760. IMO, i5 2500K and you should be able to hit medium settings w/ great framerate.
Edit: Do you guys think I would see any benefit going from 4 to 8 GB of RAM?