The only docs for PGO seem to be in the toplevel README.rst. Sinec that is what's shown to all visitors to the GitHub repo, perhaps this information is not so useful there, and instead a section could be added to the devguide? (Ditto for LTO.)

Note that for Windows this info is in PCbuild/readme.txt. It's perhaps okay to keep it there, and just mention in the devguide that the Windows info in there.

FWIW, maybe we should get rid of the tradition that the toplevel README.rst file's heading gives the version? That tradition dates from the times when source distributions were done as tarballs... It would save one more place to update (there's another mention of the version later in README.rst which still points to 3.10).