Firefox 70 will use Core Animation on Macs for graphics rendering, just like Chrome and Safari. This will vastly improve low energy consumption/battery life, but I haven't heard anything about general UI performance?
I'm on Firefox Nightly, and performance has been noticably better in the past several months.
Previously Firefox was barely usable for anything with animation on OSX. They've been making steady (if slow) progress for the past year or so, now it's subjectively on-par with Chrome and Safari for me.
Firefox performance has been a joke on mac for years with "fixes" supposedly happening every few months but it's still horrible. I'll believe it when I see it.
