Friezes (Assassin's Creed: Revelations)

I decided to pereproyti the trilogy of Ezio, and in the last part faced friezes. For a second or two salaryval game when traversing the world. It shouldn't. Iron is drawn (percent. x2 2.6 GHz, 4GB RAM, 2GB vidyuhi). 25-50 fps. Tried on medium settings, and on minimum (everything lowered (even resolution), but nvidia 3d vision - you cannot toggle the option) - there is practically no difference. A couple of years ago, they played much weak hardware (1GB of RAM and 512 MB vidyuhi), and the Frisians did not exist. What's the problem?