Currently we freeze the 3 main import-related modules into the python binary (along with one test module).  This allows us to bootstrap the import machinery from Python modules.  It also means we get better performance importing those modules.

If we freeze modules that are likely to be used during execution then we get even better startup times.  I'll be putting up a PR that does so, freezing all the modules that are imported during startup.  This could also be done for any stdlib modules that are commonly imported.

(also see #45019 and https://github.com/faster-cpython/ideas/issues/82)