It may by my particular experience by trying to import my groups from Panarama Tab Ghroups, but this extension consumed so much memory that turned Firefox unresponsive. The drag & drop functionality is sub par compared to other extensions.

It keeps crashing? Firefox becomes unresponsive and completely locks up. I have to restart start Firefox, when I check, all my groups have disappeared. It keeps happening, so I've had to uninstall.

Looks cool. I have no idea what it's doing other than creating new windows & making me worry that it's just going to lose the tabs I'm trying to save.

This esxtentio is veryuseful and worka well, However it needs a tab explaining some functions to users be able to use it.

Even the best browsers and computers crash some time or another.

It is possible to bzck up or restore the tabs. The button links are there, but not a ward about how to fo it. How to chose where from or where to.

There is also what I suppose to bve a very useful autimatic STG backup, but I cannot guess which is which with 149 files in 7 directoris. We have to do it blindly, and probably destroying what we want to repair.

If I could use the extention functions in full, I would give it 5 stars.

Lost tabs after a moment, so useless. Otherwise is the best ergonomic Tab groups add-on I tried.

Seemed nice, but when I've first time changed to a group of a few selected from many tabs it hid them without an easy way to change back to the ungrouped ones.
I've found them under the "v" tab menu and saw an option to change them into a group, which I used, as I saw no other way to get back to tabs without groups. After a few minutes of CPU abuse the "Ungrouped" group had zero tabs. 400 tabs went straight to /dev/null.
So yes, a good way to clean out your stale tabs, short of removing your profile.

Edit: Now I'm torn, as I've found out how the "Manage groups" looks and works.

When I try to open a new tab outside the group/container it just automatically gets pushed to the current open group(and linked container) I couldn't open anything in another group/container that's not the current one

Keeps bugging out. Can't use the same container for multiple tab groups. Settings are ambiguously named so I can't tell what they are supposed to do.

I don't know what happened, but from some moment extension started to hide my tabs - I couldn't find an option to disable this behavior, it is very annoying. I want all my tabs displayed in a row, not to open a list every time and search from there.

After some time this behavior is back, with v4.5.1 (FF 79)

Afer one of last updates regex for catching tabs stopped working correctly. I have some site inside my corporate network with address https://somesite/. I used "https://somesite/" filter to catch tabs with this site and it worked until some recent update. Now the only expression, that works, is "somesite", witch catches all sites with "somesite" in URL. Escaping "/" also doesn't work. It appears that any expression, that doesn't match examples in help tooltip, doesn't work (Firefox 70.0, addon version 4.2.2).
Update: Regex https?\://somesite/? works only when I open link to "somesite" in new tab inside browser. When I enter adress maually or open link from external app (i.e. Thunderbird), it doesn't work.

It used to work really well, but recently keeps forgetting all my tabs across reboots. It all started at the same time the "incognito mode" warning came. I basically became useless for me now.

I'm rating this 2 star for having a warning pop-up each time you open firefox: Please enable "Restore previous session" in browser. Even if you do have that option enabled, the warning still shows up.

Latest update bricks functionality unless it is disabled in incognito mode. I'm not interested in disabling it in incognito mode; I have been warned, thanks, there appears to be no way to disable the warning. Worked well until now.

Excellent. Only reason it doesn't have a 5-star is because not sure how to allow Firefox Sync to also sync this extension. That would be killer!

Update (Aug 6, 2019): Not sure if it's a new release but my tab groups keep getting deleted! Please help.

Sorry, The application works slowly, especially when switching between tabs and Panorama Tab Groups. This poor performance is since the fresh installation of this extension. It should be definitely improved.
I use FF Quantum 65.0.1 (64-bit) Portable version.

I'm sorry to down-vote this add-on but it's just too unstable: as others have said, it can't separate the tab groups - they end up dumped in one group all too often, or I get a tab error message and they simply refuse to load. This happens in 2 out of every 3 browser restarts. It's too much.

I love it but:
1. If firefox is not closed properly it's really really slow to reopen it and restore the tabs.
2. There is an error "Invalid tab ID"

效率低不说了，还丢组，上次重启Firefox之后就丢失了全部分组和标签。

With Firefox updated to v62 and addon to v3.1.1 it doesn't works. Tabs from one groups are shifted to others when change, and according to extensions like Copy All Tabs or All Tabs Helper, discarded tabs remanin loaded, showing rigth now more than 100, despite the current group has only 3.

Good first pass at this extension. Buggy - frequently, it will freeze up while switching tabs due to duplicate url's in more than one tab group.

I like most everything about this EXCEPT for the fact that the tabs reload whenever switching groups. That's very annoying. For example, if I download something in one tab, wait for it to complete, switch to a different tab group, and then switch back, the tab reloads and the file start to download again. That's just one example of the annoying behavior.

If it wasn't for that, I would be satisfied and would stop looking for a better tab manager. As it is, the search continues.

UPDATE: A later version of this fixed the tab reload issue, so now I'm much happier with it.

Changing groups just closes all your active tabs and opens the others. So when you switch back, all your tabs reload and you lose history (as in the back or forward button). Pretty pointless. It's about as useful as having a text file with links of your tabs, because you lose your history. This add on should take advantage of the new tabhide in the about:config and maybe that will help it work properly.
Also, even though I restore info from the old tab groups, it didnt bring the history so again i cannot hit back button. shame.