Thoughts from my 14-year-old backup Thinkpad T430 after the main laptop died:
* Github's javascript UI is SO SLOW
* Most of the rest of the web is actually not terrible (at least with adblock)
* It drives a 4K screen surprisingly well
* Video playback is bad
* How is this thing running out of RAM, it has 12GB...
* The keyboard is a delight
So it turns out that Ubuntu's Firefox Snap blocks Firefox from reading the system memory pressure, which it uses to work out when to reclaim memory by hibernating unused tabs.
Nobody thought to check why this kept getting blocked by AppArmor until someone pointed it out, and it still hasn't been fixed.
@hugh you aren't the only person who has learned this from me this week. Quite pleased that I managed to identify this issue so quickly myself tbh!
You can switch to the Mozilla-provided deb to fix this, but it will nuke your profile (you have to export and reimport) and you need to make sure that ubuntu-restricted-extras is installed if you don't want video playback to mysteriously fail.
Russ Garrett
Hugh