It happens when you get a really big change graphics wise.Traveling down the backstretch,let's say,there's not so much going on,but when you get to the corner,you're hit with signs,crowd,grandstand,and more cars in view.

You can try enabling vSync.Do it in the control panel of your graphics card.I guess a 9400 would have this option.It helps keep the big framerate changes from happening.Doing this has helped a lot for me.It still happens a little from time to time,but not nearly as often,and not as severe either.




rich