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.
@red this thing has 12GB of RAM, I don't think that's an unreasonably small amount!
I'm going to need to know how much RAM and how many browser tabs the Ubuntu devs have now.
@russss My experience of snaps was that I didn’t know they existed until I updated Ubuntu (routinely) and Firefox (1) lost its profile; (2) could no longer access the file system.
This was apparently desirable behaviour and not a usability catastrophe (where are all my bookmarks, plugins and settings, and why can’t I download anything?!)
Once I realised they’d containerised everything and it was going to be my problem to deal with that whole mess, I nuked from orbit and never looked back.
@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
Alan
Røde
Richard
Jan Lehnardt 
Miek Gieben
Hugh
Fabos (not an OS)