TC is right, but it's not BAD. There is a little slowdown (about 25 fps or so)? YES. Is it annoying or disruptive? NO. It depends on the area and if you set things on fire, but trust me that after a while playing you won't notice.
There is texture pop-up too, and this one is noticeable, you will see things "appear" at certain distance. Anyway, enjoy the game as it is because it's pretty damn fun.