Nice idea 👍 just to clarify: this "only" removes the need to download the wheels each time, but pip still need to install them.

precisely.

Can you link to a CI run where downloading and installing took 1min? I clicked around a bit and mostly found that step taking 20-30 or even just 10 seconds...

https://github.com/python-telegram-bot/python-telegram-bot/actions/runs/3825220803/jobs/6508026698

This takes 54s in the "install dependencies" tab, but it doesn't even include the one happening in pytest (after we test without dependencies). The precise time for that isn't available, but when I was looking at it live, it took about 30s or so