zlacker

As a fellow tab hoarder, I recommend Auto Tab Discard. Tabs are still open but aren't actually loaded until you click on them. With various configurable options for how that works.

I have five windows open with about 1000 tabs in each, no performance problems at all. It's great!

>>filche+(OP)
If you restart Firefox, it won't load a restored tab until you navigate to it, so presumably most of his are already backgrounded.

I find it useful to periodically prune, though. Save to Pocket or other "to read" list for things I intend to eventually read. Bookmark things I may want sometime, but don't need open. Potentially use Tab Stash to save groups of references for particular research tasks. Toss things that realistically I'm just not going to get to ever.