We've frozen most of the stdlib modules imported during "python -c pass" [1][2], to make startup a bit faster. Import of those modules is controlled by "-X frozen_modules=[on|off]". Currently it defaults to "off" but we'd like to default to "on". The blocker is the impact on contributors. I expect many will make changes to a stdlib module and then puzzle over why those changes aren't getting used. That's an annoyance we can avoid, which is the point of this thread. Possible solutions: 1. always default to "on" (the annoyance for contributors isn't big enough?) 2. default to "on" if it's a PGO build (and "off" otherwise) 3. default to "on" unless running from the source tree Thoughts? -eric [1] https://bugs.python.org/issue45020 [2] FWIW, we may end up also freezing the modules imported for "python -m ...", along with some other commonly used modules (like argparse). That is a separate discussion.