Hey, i just bought a 2011 MacBook Air with th 1.7ghz i5 and it just seems kinda laggy, the animation when switching from one space to another seems laggy and not so fluid. I had the high end MBP 15 before that and it was fluid and fast. And I know this is not a performance related problem as the MBA i tested out at the apple store was as fluid as my MBP.