I finally gave in and did a clean install of Windows 8. I'm a believer in Win 8 for this beta (and game I assume). It easily gave me 10 FPS on Ultra and almost eliminated the stuttering I was experiencing. There's still some there, but I attribute it to micro-stuttering from the SLI profile, which I assume will be fixed at release.
I also turned on adaptive v-sync on the NVIDIA panel and it seemed to make the game even smoother. Getting 60 FPS now pretty consistently on everything Ultra @ 1080p, no AA (forcing my 120 HZ monitor to do 60 HZ).
Huge improvement from Windows 7 and without the adaptive v-sync. It's finally playable!
I've had exactly the same experience. Feelsgoodbro.gif