Then, I slapped my forehead....HARD.
I forgot I had updated my Nvidia drivers to the new beta. And as with ATI drivers, a whole new lot of High Definition Audio devices appear in my Windows Device Manager...devices that need to be disabled (NOT deleted), or else they simply piggy-back my main audio device (an external USB one) and bring my CPU to its knees. This one time, I forgot this step, and I feel stupid for wasting hours fiddling with every other setting to try and fix my stutter. Stuttering = gone.
I've heard many have micro-stuttering also, so hopefully this may help some.


The reason this works for some people is that if you are pushing the game to the utmost limit of your cpu, the multiple audio devices all being active eating up valuable processing power is enough to push you into stutter-ville. Learned this from a guy named Irishron at twcenter.net a few years ago.