I have to second this, we have a JS based game engine and Firefox is very much noticeably slower than Safari and Chrome in terms of JS performance. I agree with

I have to second this, we have a JS based game engine and Firefox is very much noticeably slower than Safari and Chrome in terms of JS performance. I agree with Iain below that in the long run this will mean moving more code to wasm so hopefully the tooling there improves. Right now all it does is move users of performance critical web-first software away from Firefox. Although I’d note that performance is utterly important for normal applications as well. Being noticeably snappy and prompt is great for UX.