It works fine on my 2011 15" macbook pro with Firefox 54.0b4. I wonder if it is the high retina resolution thats the problem for you?

It takes up about 2 percent of my 7 year old cpu in chrome. It is also compiled from Unity, so was not made from C++ directly.

Apple's OpenGl support is crap.

> Why is WebGL still so heavy on the CPU?

Well, how else are we supposed to get nice side channel / timing attacks?