Its normally where there is a corner. for example if im going along the wall and there is a right turn ill try and make the right turn but half way round the bend it'll stick and freeze for about 0.5 seconds.

same with going up the giant ramp if you go near a wall ur freeze for a short space of time..... its like its lag but there is nothing wrong with my comp or graphics card.

if I can in the next couple of days ill create a fraps video or something as im useless at explaining things lol.