Ok...very similar to 2010 stuttering but.....first of all the replay file is read only......I can do approx 1 lap and then the stuttering starts, if I alt-tab out (games goes to 'pause' & window mode), then alt-tab back in its perfect again for another 1/2 lap or so, then starts again, I can reproduce this every time!!! Normal frame rate is over a hundred (everything max).. while its stuttering if I sit on the track or crawl along the drivers head twitches in unison with the stuttering???? Any help to stop me commiting suicide....I'm sure CM still havent ironed this out....it makes no difference what graphic options I change.. win7 64, 8 gig ram, GTX 560ti, AMD965 quad @3.4 nothing overclocked