I'm curious (genuine curiosity, not meant sarcastic), why is Firefox only now switching to CoreAnimation? AFAIK CoreAnimation has been around since Leopard which makes it nearly 12 year old, which is positively ancient in the tech world.
Also, coincidentally, do you know what exactly causes the H264 problem on macOS? I've tried to track it down in bugzilla to no success, but I am 100% sure it is a bug. The energy impact for playing a H264 YouTube video in Safari has an energy impact of ~25. Firefox used to be ~60, but these days its ~180 (!)
> In the meantime, setting gfx.compositor.glcontext.opaque to true in about:config helps battery life significantly, at the cost of rounded corners and vibrancy.
Thanks for this! :)