My rFactor still stutters! When I play online, first laps are ok, but the rest of the race is like driving with 17FPS, but It shows me that I have 60-70 FPS. I have same problem with SimRaceWay. Where is the problem? CPU? My internet connection is good - 8Mb without problems in another games. CPU OCd to 3,0GHz Core2 Duo 4GB RAM GTX470 1920x1200 Thats why I dont play rF2 because it doesnt look nice and its not optimalised... but physics, cars, weather, tracks are good.
Maybe use video sync (configure sim options). Update your gpu drivers also if you haven't done so. Maybe lower some settings?
I had this problem and it was my CPU. Use CRTL-C to look at how hard your CPU is working. You don't want the purple bar to be very long otherwise your CPU is working to hard http://isiforums.net/f/showthread.php/2258-CPU-time-graph-what-does-it-show
