Unrelated to that, but on a Ubuntu laptop I have Firefox tabs regularly stop working entirely. They just won't load anything, and the only fix is to open a new tab and that loads fine most of the time. Other times I have to restart Firefox. I've tried searching for others experiencing this problem and even asked in Mozilla channels on Matrix, but even then I didn't come up with any answers. The laptop's hinge broke last year so I haven't used it since then, so likely never going to figure out what was going on.
Update your firefox now and the issue is gone.
It was basically the whole reason for the update.
Google changed their code to create a bunch of objects over time, and those objects didn't get cleaned up. It was just a standard memory leak issue.
Except it heavily impacted users who kept a youtube tab open or pinned.
The bug was reported and a fix released in a little under 2 weeks.
I have over 1200 tabs open at the moment, including at least 100 youtube tabs, and mine runs fine even with a bunch of other stuff running.
I do find that if I go over 150 windows open then things start to become problematic, but I think that's because my GPU is only 8Gb.
CPU is usually at about 10% on an i7-12900k.
I expect YT is probably doing some preloading or heavyweight running in a loaded-but-not-playing tab.
Convert that to load-on-click, and you'll likely fix your issue.
The fact is, it doesn’t happen in Chrome for “magical” reasons, according to a comment few levels up. And regular non-tech users won’t debug this with click to play or whatever. We expect that YT does it absolutely intentionally.
It bends userbases however it wants due to its multi-dimensional reach, and we’re like “hmm maybe extension would help prevent accidental preloading issue”. I just don’t get it.
What a strange confusion, as if all people must have the same "workflow". Sorry, no intent to sound negative, but why not give it some thought at least. It's "6 tabs", not "6 videos playing at the same time".
This seems intentionally YouTube's UX design fault, they too heavily try to push you to "auto-play". YouTube has a "Watchlist" feature where you can build a playlist. When it works it is exactly what I want, but it feels like every so many months it mysteriously breaks for a while or they hide the button for it behind some new hidden gesture or menu they expect you psychic out of their UI. (If you've never heard of "Watchlist", no wonder. It seems intentionally hard to discover.) Lately I've been complaining that YouTube adds random "auto-play" videos even to a manually curated "Watchlist" if you don't pay enough attention or watch past the end of the list (even with auto-play and recommendations entirely off).
I’m still using Watch Later, but for long videos I have no time for.