Ha! I was just playing it! First time, awesome game!
Yeah sounds like the CPU is struggling. I have AMD's Six-Core Phenom II X6 1090T @ 3.7GHz OC and it's great.
I'd go for 6 cores just to be sure.
And I have the 6950 too, awesome card.
I can play it on ultra with no fps issues...
Hope you get it fixed and enjoy the BF3 to the full.