Import time regression

[holmanb]

Between 2.31.0 and 2.32.3, import time increased by ~25%. This appears to have been caused by #6667, which changed the expensive load_verify_locations() to run at import time (in 2.32.0).

Reproduction Steps

Compare import time of versions with:

$ python3 -X importtime -c 'import requests' 2> requests_import.log
$ tuna requests_import.log

2.31.0

2.32.3:

[donno]

I'm on Windows, with Python 3.11 and requests 2.32.3 and noticed very slow import times and narrowed it down to requests. In my case when importing requests, the requests.adapters module made up 4.353 s (85.9%) of the import time with similar command as above.

[seproDev]

We noticed that this slows down yt-dlp startup time by ~50%.

yt-dlp provides its own SSLContext, so the one created by requests on import remains unused.

Is it still planned to revert the caching of a default SSLContext (#6767) or should the SSLContext no longer be created on import as proposed in #6791?