I am also having a similar issue. I was on my Sylvari Guardian going to AC and once I ported to the Charr city my FPS went below 10. Anywhere else in the world my FPS is quite high. Once I exited the Charr city and made my way to AC my FPS was so greatly reduced (1-4FPS) and my Graphics Card Driver crashed. I’m believe my driver version is 304 or 306 (nVidia GeForce 660 Ti). I didn’t have any issues in AC, but the Charr zone and city are the bane of my computer. Lion’s Arch was slow but there’s a lot of things going on.