I have no idea what you people are doing. I use FF with my mid spec, 4th generation i5 with 500+ tabs and haven't experienced any of your problems.
When I did research about it (about a year ago) it seemed the devs were considering retina macbooks with a non-default resolution as origin of the bug for some reason - I'm referring to the display setting that appears as "more space" in the regular OSX settings menu, not some arcane hidden configuration.
I regularly check back because I love the idea of using their open source, somewhat privacy-focused alternative to chrome, but it's been years and still not a fix in sight.
To me it seems that a large segment of users using the Retina screens (most people on the osx platform) has severe performance problems. Some people have no problems. And that is just the state of affairs.
The weird thing for me is that there is no official "issue" or information about the problems since so many experience it.
Seriously wanted to switch to Firefox after the browser-sign-in "feature" but the performance on my high-end 2018 macbook pro with 16gb ram was just abysmal (20 tabs open tops).
I'm using Tridactyl for navigation, so i just press 'b' (:buffer) and start typing tab title or whatever. In a moment I'm on the tab that I needed.
There are a few handfull addons for tab management available.
>know what’s on those tabs?
I was the one who opened them, of course I know what's on those tabs.
I rarely have more than 10 open at a time and sometimes completely forget what's there or why I opened it - I find uber-tabbing impressive and baffling in equal measure.
If you know what you're looking for, what does having it open (but probably knocked out of memory?) have over using search/URL autosuggest? Just a workflow thing, or is it faster?
I think of my tabs as my documents (the ones I'm working with today, this hour or even this very moment).
I prefer keeping those documents on my table, because this saves me some time\effort and just more convenient (subjectvly). So active tabs are the documents right in front of me and knocked out of memory ones are the ones I'm going to work with soon or needed for some sort of reference waiting their time in some sort of document organizer.
>I rarely have more than 10 open at a time and sometimes completely forget what's there or why I opened it
Well, I just have good memory :D It's part of the way schooling goes here in Russia I guess and maybe the upbringing. Memory training was just another daily routine. Sometimes it's really hard for me to believe that some people can't remember the plot or the characters from the book they read a year ago, while I still can quote a book I read 15 year ago.
In the end I guess everything goes down to what kind of processes influenced your brain development or something like that.
I typically have related tabs around the one I find. E.g. recently I researched some details about the python requests library, but haven't finished implementing it yet. I can go back to that group of tabs that's in a somewhat logical order. Autocomplete wouldn't have that, and also suggest links I've already discarded as not interesting.
I've tried a few times to replace this workflow with bookmark groups etc, but I never got that to work in a way I'm completely happy with, and making my own extension that does it exactly like I want it to would be an interesting project, but too much work for now.
What I find useful is a browser extension that lets me copy-paste a list of all URLs in a window with their titles, so at the end of a research session I can move the entire list quickly to a markdown file and save it with a few notes.
This doesn't really help with navigation when you have 100+ of them, but this structure maps to your internal memory organizer too. Sort of.
It's like orrganizing things you keep in your room\apartment - you may have LOTS of things and from a 3rd person point of view they may seem unorganized, but not for you - you put things according to your own logic and even if you forget the exact coorditanes of some item you still can find if quick enough because you know where you should look for it.