Thank you, I’m very happy to finally see Core Animation being implemented. Prior to this update I literally couldn’t use Firefox because it would spin my fans way up and slow down my whole computer. I’m seeing a huge improvement over here too (2015 13″ MacBook Pro with scaled resolutions on internal display as well as external 4K display). Users have reported much longer battery life, cooler machines and less fan spinning.
The larger the Firefox window and the smaller the animation, the bigger the difference. In short, Firefox 70 improves power usage by 3x or more for many use cases. Power usage, in Watts, as displayed by Intel Power Gadget. As a result, Firefox 70 drastically reduces the power usage during browsing. This allows us to do less work per frame when only small parts of the screen change. In Firefox 70 we changed how pixels get to the screen on macOS.