Firefox 85 declares war on supercookies, enables link preloading and adds improved developer tools (just in time, since Google's playing games with Chromium users again). This version builds and runs so far uneventfully on this Talos II. If you want a full PGO-LTO build, which I strongly recommend if you're going to bother building it yourself, grab the shell script from Firefox 82 if you haven't already and use this updated diff to enable PGO for gcc. Either way, the optimized and debug .mozconfigs I use are also unchanged from Fx82. At some point I'll get around to writing a upstreamable patch and then we won't have to keep carrying the diff around.

https://www.talospace.com/2021/01/firefox-85-on-power.html