Hi, On our fourth MBA over the last few years. Previously had 2010, 2012 (13), 2012 (11), now a 2013 (13 base model). I have to say that the 2010 model running SL was the fastest, but that's subjective. Our 2013 base 13-inch seems a little reluctant to get up to speed. There's always a delay before it does anything, almost like a HD is booting up. Also, we've seen 182% on the CPU on Activity monitor with nothing open except a kiddies game (Bridge Constructor) from the App Store. The fan is going crazy, I don't recall ever hearing the fan on any of our previously models. Finally, despite charging the battery to full, then running to empty, then charging to full on the first two cycles, battery life is no better (around six hours) than our 2012 model. This is just running Chrome (nothing else) with around four tabs open. I guess we got a dud and it needs returning within the first 14 days, or is this the best we can expect from Haswell? Perhaps the i7 would be better? Cheers.