I have a 2600k @ 4.9ghz and Im not stuttering.
I just did more FRAPS runs on ULTRA settings @ 1440p and the average of them was 65 FPS. Multiple maps, multiple scenarios to get a variety. Lowest average run I had was 54 FPS, highest was 71 FPS and most were in the 60's somewhere.
I didnt even think about trying windows8 yet. I wonder if it really runs better on Win8. Im on Win7.
I'm on 8.1 here.