I agree, I'm the same. People who sneer at large tab collections don't seem to realise that when they can be put to sleep, tidied away (various extensions allow groups to be folded), they are more like advanced bookmarks and working context. Or, they think there is no justification for having such collections.

For me they are working context for different projects over years. Working on project X a month ago? 6 months ago? Great, I can go back to where I was. People have told me I "need" to close all tabs and if I need working context, copy links and notes into some kind of knowledge-base. But I tried that, and in practice a "context switch" from project X to activity Y takes hours and occasionally days to write up. Making knowledge-base notes is valuable, I do it sometimes, and that's how I know how long it takes me. But it takes a long time so it's not always the best use of priority when activity Y beckons. There is usually not enough time.

I asked people what they do to tackle my sorts of projects. The answers were always the same: Some ums and ahs, and it turns out they don't. They just don't take on the same kinds of things. I would really like to learn from highly productive "clean desk" people, working on similar projects to mine, how it is done, but to the best of my knowledge I've never met one.

So sleepable tabs it is for now. There's still room for better organising. Tree style tabs aren't very searchable. The content of the pages is even less searchable, and it would be helpful if there were a way to go back in time to an earlier snapshot if the page is removed. I would really like them to be integrated into other tools. I tried Org-mode (I use Emacs all the time) but the one feature lacking in Org-mode is the ability to capture and show a collection of web page content decently, so it hasn't worked out for this kind of knowledge capture. There are commercial tools that claim to be what I'm really looking for, but I'm not going to store such a major part of my working life in closed commercial software.

I had to stop using the Tree Style Tabs extension for Firefox, unfortunately, because it was slowing down the browser terribly. This wasn't Firefox, or the tabs. It was the Tree Style Tabs extension.

It's probably some trivial algorithmic O(n²) somewhere, but it reached the point where opening a tab or clicking on a tab, or doing other things in Firefox that should be near-instant would take 5+ seconds, and the browser would take 5 minutes to start up, even though almost all tabs start up asleep. There is no good reason to be this slow, because most tabs are unloaded most of the time in Firefox. And indeed when I disabled TST but kept the tabs, everything became fast.

Sidebery. After trying out other extensions I settled on Sidebery, which is working out well so far. In particularly, it's very much faster than TST for large numbers of tabs, and doesn't appear to slow down the browser during non-tab operations. It's also working out nicely for me in other ways, and works reasonably well with containers.

(There are some quirks: Dragging sometimes just fails, refuses to move some tabs, or a tab even "disappears" until Sidebery is turned off and on again. Moving a list of tabs to another window can be very slow, about one a second. The "panels" tab-grouping feature is odd because it's the same list of tab-groups in every window, which doesn't make sense; in most of my windows there are empty panels as a result.)