Unfortunately the biggest problem by far is video playback and for whatever reason they seem to refuse to fix the problem.

Here is a simple test I just ran:

Using https://github.com/erkserkserks/h264ify for blocking VP9

2015 rMBP 13", 3.1Ghz i7, 16GB (defaults to software rasterization in chrome)

https://www.youtube.com/watch?v=nK9Im1eP3DI (1080p60 video)

Power is CPU Package Total (core + GPU).

Chrome VP9: 26W

Chrome VP9 + Force GPU Acceleration: 28W

Chrome h264: 19W

Chrome h264 + Force GPU Acceleration: 13W

Safari: 4W

Additional comments:

This is all in window at the default 'theater mode' size of youtube. I can't full screen either of the VP9 options without completely maxing out the CPU, dropping frames and during my laptop into a frying pan. Its really hot even in window with chrome VP9 using ~175% CPU.