Ubisoft it up hard again, I have a phenom II 955 OC to 3.5ghz and a 5850 with latest 11.3 drivers, and it stutters like hell, either vsync on or off, disabled two cores, run as admin, xp mode reset OC to default, neither patch 1.01 nor latest 1.02 made anything.
Also I play at 1360x768 on a HDTV. It bothered me enough for uninstalling the POS they made us wait for for 5 months and getting a refund, last time I buy a sh*tty ubisoft product.
Search around on google and there are loads of people having the same issues, both amd and nvidia users so it's not a driver problem.