I'm a hobbyist/part time iOS app developer, and I currently use a first generation Macbook Air (80GB 4200RPM, 2GB ram, core 2 duo 1.6) for Xcode development. Unfortunately, I can't upgrade the OS to the newest version of OSX. Also, unfortunately, the hard drive is failing. Although I suppose I could replace the hard drive and keep using the old air, I can't upgrade the OS. And, my guess is that the next version of Xcode will require Mountain Lion. So, I'm in the market for a new computer to do Xcode work. My experience with my current air (which was handed down to me) is that it's very slow at running Xcode. I'm looking at a 13" MBA with a 128 GB SSD, as that seems cheapest option aside from a mini. However, I'm concerned that the machine isn't powerful enough to really run Xcode well. So, how much of a performance improvement should I see in Xcode? I'm not really concerned with compile-time improvements. I generally just want a snappy and responsive Xcode. Would I see much of an improvement from an air going to something with a dual core i7? quad core i7 - or is a new MBA with an i5 "good enough"?? I'm okay on the screen real-estate. 1440x900 is enough (though I certainly would appreciate more) - and I can always add an external monitor. Thank you!