CoD BO II CPU frequency demanding?

Is call of duty black ops II cpu demanding on the speed of each core? I looked at a few articles saying that its still only optimized for a dual core to a quad core and not really on the speed, but then saw another that mentioned that clock speed matters like it did with WaW and black ops I. Was playing and my 6 core currently at 3.2Ghz was lagging and being used more than my HD 6770. Using HWinfo64 total core usage reached 96% where watching gpu usage and frame rate was ranging from 50-75%. Beside running steam and the game, was only running itunes, the monitoring programs, and other small background programs, so dont see much use coming from those. Im just wondering as with the same specs i play bf3 with the same 1080p monitor, on high preset with 30-35fps and black ops II with the default settings it choose with shadows moved to medium and depth of field to medium with anti aliasing to 4x msaa and fxaa on and texture filtering on high i get from 30-60 fps but avg is prob similar to the bf3 fps 30-40. But unlike bf3 my cpu is only near 75% and gpu 99%, and almost no lagging or stuttering, BO II has lag and stuttering with not even close to 99% gpu use.

Is this due to cpu clock speed? or what?