I dug some old computers out of the attic recently. The one that had not been updated since 2021 only took around half an hour to get up to speed, and that was with a metric ton of packages installed.

The other one seemed to have been updated last time in 2015. It didn't even have updated certificates for https, so it couldn't sync the keyring. After trying for a while I just gave up and reinstalled Arch from a USB stick.