I dislike the will-change property and wish they’d left it at the obviously-a-hack `transform: translateZ(0)`, because the whole thing should simply not be necessary—everything should be rendered on the GPU, and that’s the clear way forward; formalising the will-change property legitimised the prevailing architecture at a time when Servo had already demonstrated with WebRender that it was possible to do better; and so Firefox now uses WebRender and does all rendering on the GPU (on most platforms), so that will-change is, I think, simply rendered obsolete (except for platforms that it can’t yet GPU-render on, because GPUs and their drivers are so awful). See https://hacks.mozilla.org/2017/10/the-whole-web-at-maximum-f... for more info on the whole WebRender performance thing.