After loading a map in UT3, before pressing fire, you can fly around the map. The stuttering is like a 1/4 second pause while moving and happens about once a second. Like I said, it happens the most in all UT3 based games. If you have UT3, you try flying around a map. This way you will be able to examine without getting blasted by flak and rockets. Also happens after the battle starts, while walking. Same kind of stuttering.