I am genuinely interested: why so many and how can you handle 400 open tabs?? How do you navigate between them? I am lost as soon as I have more than 10 tabs open at the same time...
Second, when you type stuff into the address bar Firefox searches through opened tabs and suggests switching to that. This minimizes the number of times you'd open a new tab.
Third, there are many addons that help you organize your tabs. There are ways to search for tab content, group them into containers, find duplicates, etc.
How to start having many tabs open? Just change your MO when you use the browser. Want to search for something? Hit new tab and go. Researching something? Open every link you find somewhat promising in a new tab. When you have 200+ tabs opened, another 8-12 won't be a big change. Done with your research? Why close tabs? Just keep them open in case you'll need them later.
Often when I work on a project for, say, half a year I don't close tabs at all, and keep getting back to stuff I accidentally stumbled upon 2-3 months ago. It's very helpful at times to be able to dig stuff up one tab away. One could argue that bookmarks and history could be as helpful, but in practice when you switch to an old tab you see the context around it. What else I was looking at at that time, often information in the neighboring tabs is relevant, yet bookmarks and browser history don't have a good UI to surface it if front of you.
Yes, your browser becomes a memory hog, but as people noticed Firefox has means to compensate that. At 200+ tabs it consumes significantly less memory than Chrome (even with Chrome's load on demand turned on).
It takes time to get used to, and ones or twice a year you'd be doing tab cleaning, but I've being using browsers like this for 15+ years and really see benefits in this workflow.
For context: right now I have 330 tabs opened, Firefox consumes 1.8 GiB of RAM
This is how my Firefox looks like:
https://dosowisko.net/Screenshot_20171030_203716.png
https://dosowisko.net/Screenshot_20171030_203804.png
Once a while I'm getting to 1000-2000 open tabs and this is a point where the whole UI starts to feel a bit heavy, which is the only reason I clean them up then - navigating is a non-issue.
It's a symptom of my non-optimal behavior. Blame the wetware between my ears. On any given moment, I might have perhaps 5-50 new tabs that I actually work in, closing them as I go along (but along those numbers). The rest are mostly left-overs since previous days.
My weakness is eg "this is an interesting read, but I don't have time now", or "this is a good reference, better save that". Over time, those add up.
To actually make it work, I set FF to not load tabs until focused. Then, when I start up, there are in reality a couple of hundred place holder tabs where I can see the icon and page name so I can find them again.
The second enabler is the plugin to have the tabs vertically, in a list on the side, instead of horizontally on top.
I really should just close them all and never look back, but I gotta admit, it's hard to say goodbye to dear friends. In this case though, I only know them by name :P
API documentation. It's very, very useful to have the structure of the APIs represented in a tree of open tabs. It gets messy eventually, but the groups can be easily rearranged.
Later on TreeStyle Tab came out, and I've used that ever since. I've got 501 tabs right now (thanks tab count extension), I usually go on purges every so often when it gets around this high and close large groups of them, reading some before closing, bookmarking many of them before closing with a current month/year annotation and other tags, so I can get back down to a more reasonable ~100-200. Even if it didn't have its tree collapsing functionality (I've got 25 tabs collapsed in a tree right now related to setting up and using some new software I started doing last night, it takes up one tab of space when collapsed) I would still use it just for the fundamental insight that with widescreen resolutions being standard vertical screen real estate is much more important than horizontal real estate. Admittedly that's not as big an insight anymore with 4k screens (and I use a big 42inch one). Anyway with TreeStyle Tab I can have tabs that are on the left side of the browser, that grow down, with scrolling, but I can still read the titles of each tab unlike in Chrome where each tab after ~10-20 is just an icon (at best).
The URL bar is also just superior to Chrome's. It's not called the Awesome Bar for no reason. The table at the bottom of https://support.mozilla.org/en-US/kb/awesome-bar-search-fire... has a list of commands you can use to match things -- I actually often have that page in my sea of tabs since sometimes I forget a couple sigils but I found it immediately with ctrl+L + "awesome %".
This submission's title is kind of hilarious. Firefox never went away, I started using it pre 1.5 on a Windows 95 machine and though now I use Chrome/Chromium for some things I've never felt the need to leave Firefox. Well, except until recently with the Quantum updates, ironically. For my personal desktop, I'm still pre-Quantum, it works just as it always has, while on my other machines I've been giving the new Firefox a fair chance and am just hoping it gets better. The tree tabs addon port especially isn't as good, I really miss my right click context menu for noscript, etc.