@Pablo
> I disagree. This is a regression/bug and we don't advertise "known bugs" in the what's new, the same for any other bugfix that has been delayed until 3.10.1

Alright, in hindsight 3.10 What's New was a bad suggestion on my part. I wonder if there's a better location for such news though.

>>  Some use cases are slower (by >10%!)
> Can you still reproduce this with PR 28475?

Yes that number is *with* PR28475. Without that PR it was worse. The second pyperformance comparison in this file is 3.10a7 vs PR28475 https://bugs.python.org/file50293/PR28475_vs_310rc2_vs_310a7.txt. Omitting python_startup (unstable on Windows) and unpack_sequence (microbenchmark):

- logging_silent: 250 ns +- 7 ns -> 291 ns +- 10 ns: 1.16x slower
- hexiom: 14.0 ms +- 0.3 ms -> 15.7 ms +- 3.0 ms: 1.12x slower
- logging_simple: 16.1 us +- 0.2 us -> 18.0 us +- 0.5 us: 1.12x slower
- nbody: 215 ms +- 7 ms -> 235 ms +- 4 ms: 1.09x slower
- logging_format: 17.8 us +- 0.3 us -> 19.4 us +- 0.5 us: 1.09x slower
- richards: 104 ms +- 6 ms -> 112 ms +- 3 ms: 1.08x slower
- xml_etree_parse: 218 ms +- 3 ms -> 235 ms +- 3 ms: 1.08x slower
- sqlalchemy_imperative: 34.5 ms +- 0.9 ms -> 37.1 ms +- 1.1 ms: 1.08x slower
- xml_etree_iterparse: 158 ms +- 2 ms -> 168 ms +- 2 ms: 1.06x slower
- pathlib: 255 ms +- 6 ms -> 271 ms +- 3 ms: 1.06x slower
- pyflate: 963 ms +- 10 ms -> 1.02 sec +- 0.02 sec: 1.06x slower
- unpickle_pure_python: 446 us +- 11 us -> 471 us +- 9 us: 1.06x slower
---- anything <= 1.05x slower is snipped since it could be noise -----

At this point I don't know if we have any quick fixes left. So maybe we should open another issue for 3.11 and consider factoring out uncommon opcodes into functions like Victor and Mark suggested. We could make use of the opcode stats the faster-cpython folks have collected https://github.com/faster-cpython/tools.