Couple of things
I'm really happy now to performance but only way i can fly London stutterfree is lower Texture Quality to High, with it i don't get stutter over a london. With Quality i got really bad stutter over london(many sec pauses). Maybe my Videocard memory is not enough.(1gig)actually (2gig but crossfirecard so real totally is 1gig)
Secondly
I use Fraps to check my framerates, i usually go first to Crosscountry, usually i get steady 60FPS when game starts and really stutterfree then. Sometimes when i start the game and go Crosscountry first it go below 40fps and little rubberband effect on low flying, i don't know why, same place, same time and same settings. If i get below 40fps i quit the game and restart, go back to crosscountry and its 60FPS again. I don't know why it behaves like that, is my crossfire card not always works or something similar. It's a luck if it is smooth or not
But now i can play and really happy with it. Love new prop.