Be ye forewarned... do not jump right into this or any other open tab manager if you have a lot of currently opened tabs that you expect the extension to help you sort out.
My fault really, but intending to just look around, I hovered & then clicked to stash on a filtered selection. Not seeing a way to pause, cancel or undo; I could only let it run. How bad could it be?
It not only "stashed" the ~500 tabs from the filtered selection, but threw the other 3200 tabs in with. Then to my horror found that it put every single one of the 3700 tabs into "hidden tabs".
I only learned of this after a frantic race to shut down every other process & service on the machine to free up as much of the 32GB as possible, praying that Fx wouldn't crash.
It finally ended, and after wasting a bunch of time trying to find a solution, have now resolved to spending more time cleaning up the resulting mess than it would have taken without the help of the extension.
Badly needs an Undo. Badly needs Select/Unselect All on filtered lists. There's not even the ability to Tap-Space to keep selecting in a list, it's a slog of one-click-at-a-time. Badly needs a setting to only affect what is selected and don't mess with anything else.

While the interface is great, the main reason I got this was to save memory. I'm not sure if this is a Firefox issue or an issue with the extension itself, but the tabs that are stashed still take up memory.

Isn't this extension meant to hide/close active tabs when you stash tabs??

I have tried multiple times to use this add-on because the promise of it is great. However, most recently, I just lost all my tabs to it by stashing them all, then searching for all the redundant tabs I had open of my email, and closing them. This turned out to delete all my tabs, not just the email, irrecoverably. If anyone knows a good tab manager which closes tabs and saves them and lets me delete whole groups of tabs without deleting everything, I would be very interested.

Also, you should keep in mind that the tabs here are not closed but simply hidden.

Cluttered and too complicated for what I want which is just saving groups of tabs and restoring them. I don't need so many settings and buttons and behaviors, making it a chore to use.

2.12.0.1 version. Icons for control buttons in the side bar under "Open Tabs" or "Unstashed Tabs" are not visible. You can only tell what the button does by waiting for a mouse-over tool tip. I wanted to try out the full page tab group management but am uninstalling before finding it. RAM use was not affected by activating this extension.

Not Working for LibreWolf side bar is blank cant access tabs but can stash them just can't use it.

I wish there was a confirmation before closing tabs. I accidentally closed my 100+ tabs I was hoping to organize with a misclick, and was unable to restore them. I will not be using this add-on in future.

Firefox slowed down too much to use it after I installed Tab Stash, I did not meticulously troubleshoot the issue, instead I Reset Firefox and today I researched re-installing Tab Stash but after reading reviews with similar reports of Firefox slowing down I decided not to try it again.
I am using an i7-6700K 4 core CPU running windows 10, which is still a decent powered computer so I really do not know if Tab Stash slowed my computer or just Firefox. I gave Tab Stash two stars for a great list of features, maybe I will try it again in a few months.

Whenever I turn on this add on, firefox starts to take 60%-70% CPU usage. Had to remove it though the user experience is good. Hope the developer can help solve this issue.

Was pretty excited about this, but was having trouble stashing tabs - Eventually realized that the tabs have to be UNPINNED in order for the stash functions to work as intended? I kept selecting multiple pinned tabs and trying to stash to a group but it wouldn't work that way unless they were unpinned. I have at least 15-20+ tabs pinned at all times and having to unpin them to stash in groups is kind of a deal-breaker :-( If I am missing something please respond!

J'aurais bien continué à l'utiliser, mais ce n'est pas en français. Je préfère désinstaller cette extension, qui est pour moi et je pense pour d'autres personnes dans mon cas, inutilisable.