fun fact, you can kill all firefox background processes and basically hand-crash every tab and just reload the page in the morning. I do this every evening before bed. `pkill -f contentproc` and my cpu goes from wheezing to idle, as well as releasing ~8gb of memory on busy days.
("Why don't you just close firefox?" No thanks, I've lost tab state too many times on restart to ever trust its sessionstore. In-memory is much safer.)
Yeah, I found this out the other day when my laptop was toasting. In hindsight, probably related to archive.today or some Firefox extension.
You have to close Firefox every now and then for updates though. The issue you describe seems better dealt with on filesystem level with a CoW filesystem such as ZFS. That way, versioning and snapshots are a breeze, and your whole homedir could benefit.
FWIW: the Tab Stash extension has worked well for me.