I'm still having issues with stuttering while looking around. It's much more pronounced when I look diagonally then pan up and down or side to side. I've tried turning up and down all the graphics settings to no avail. I've tried windowed mode and it makes no difference. I've tried turning off mouse acceleration. Anyone have any idea what to do?

Look here, it might help.

http://www.gamesas.com/topic/1374789-new-amazing-mod-to-increase-fps-hialgoboost/