I don't know what Xcode is doing, but I am certain even a very dedicated and proactive IDE spends most of the time waiting for keystrokes. There is _no_ reason why Xcode could cause this behaviour.

BTW, I am very happy with my Atom-based netbook for developing stuff with Django. There was a time when developers needed a lot of power, but those days are long gone and today it's the guys who do video editing/encoding, manipulate huge datasets and play games that need the big computers.