I run Windows Task Manager all the time (to guide me in maintaining RAM usage below 80%). I tend to have 4-10 Firefox windows open; if careless, I allow enough open tabs (e.g., RAM usage) to slow or crash FireFox/Windows.
The ability to quickly save (~all tabs) and CLOSE a Firefox window, helps me avoid Firefox/Windows crashes.
On 6/24/2020, I discovered FoxyTab, which
allows me to quickly copy almost all
URLs (in the "current" window of FireFox)
to the clipboard, and then paste them into a file (to save "where I'm at" in the Firefox window). (Optionally, I usually include Webpage-Title for each tab.)
With FoxyTab, I can even do this fairly quickly for ALL my Firefox windows.
Afterward, I can winnow/add-to/rearrange the "tabs" within that file.
FoxyLink AddOn allows me to later restore (~all) those tabs within a Firefox window,
often after (to free-up RAM) I reboot FireFox and/or Windows.
I have found both FoxyTab and FoxyLink to be highly reliable, and reasonably straightforward to use, though I often have to review FoxyLink usage instructions; the two AddOns have slightly different orientations.

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Great extension. Needs 2 features found on Firefox v56 and before, though. You can use Waterfox with the Classic Theme Restorer to get these features, but they have regrettably disappeared in FF v57 and above. Waterfox is from the mozilla version 56 code base and still supports virtually all of the legacy extensions, but is starting to get a bit too bloaty and, even with no add-ons loaded, has memory leaks that can bring it up well over 2 GB just sitting open for 24 - 48 hours. Still worth looking into for those who lost add-ons they can't live without since FF re-wrote its engine in version 57. It can also use current FF extensions like FoxyTab, btw. It shares profile information with your current FF & can run concurrently.

1. Ability to locate tabs right above display windows, under the bookmark bar. Infinitely better user-friendly design.

2. Allow for tabs in a designated number of multiple rows instead of extending the tabs off the end of the screen and needing to arrow back and forth to get to unexposed tabs. For those with a number of tabs open at a time, this is the best way to display all tabs without resorting to gimmick.

Those two additions would bring FoxyTabs up to a solid 5 stars and more.

je vais essayé Foxy Tab

excellent concept and very useful and versatile.