LTO-PGO is still working great in Firefox 83, which expands in-browser PDF support, adds additional features to Picture-in-Picture (which is still one of my favourite tools in Firefox) and some miscellany developer changes. The exact same process, configs and patches to build a fully link-time and profile-guided optimized build work that were used in Firefox 82.

Dan Hor'ak has filed three bugs (1679271, 1679272 and 1679273) for build failures related to the internal profiler, which is still not supported on ppc64, ppc64le or s390x (or, for that matter, 32-bit PowerPC). These targetted fixes should be landing well before release, but perhaps we should be thinking about how to get it working on OpenPOWER rather than having to play emergency games of whack-a-mole whenever the build blows up.

https://www.talospace.com/2020/11/firefox-83-on-power.html