Therefore i suspect this is mostly down to a lack of hardware power however i would recommend trying some of the fixes listed on their FAQ either way. 8GHz below what it is supposed to be (macs tend to do that a lot). this isn't spectacular by any means and is actually well below what Dolphin recommends and very few users have listed chips of that grade as working and all of those were at stock clock speeds not. If you are using a 2014 macbook air you likely have a down-clocked dual core i5 4250U chip and 4gb or ram using onboard intel 5000 graphics. Download Dolphin for Mac - A free and very useful application designed to act as a GameCube or Wii emulator and to bring the console gaming experience to. This inefficiency can lead to some emulators requiring much much more powerful hardware than the original console did. This is why most emulators have problems even on very high end hardware and in some cases having too high end hardware can actually break games by making them run too fast for their engine. The gamecube is built to run gamecube games and the Mac is built to run x86 applications in a Linux environment.

First off comparing the raw power of your macbook to the original console isn't a valid comparison.

Dolphin emulator mac gamecube