As per reddit:
This example app seems to have abnormally high CPU and energy usage when compared to the 'Lister' sample app from Apple, and it's far more complex than this little demo.
I really wouldn't want to be running an app on a MacBook or iOS device that kills my battery when compared to the Apple design patterns. We see libraries like this pop up - all of the time, as if Apple has never been down this road before, or they don't experiment internally.
https://developer.apple.com/library/mac/documentation/Performance/Conceptual/power_efficiency_guidelines_osx/index.html#//apple_ref/doc/uid/TP40013929-CH15-SW1
As per reddit: