I've been holding off updating Firefox until this add on became stable. Over the last week I have been running it in in parallel with my production environment with ~ 150 open tabs in 5 groups and had no issues with load times, overall performance or stability.
Consequently, I have today fully transitioned to FF V65.01 and Simple Tab Groups.
Am very happy. Great work! Thank you.

First, thank you for this fantastic add-on. Congratulations, is a very nice work.

Second, this add-on deserves all the stars. But I am going to give 4 starts, just because the delayed start-up issue (it takes lot of time to launch in my FF). This is a small issue, and only happens at FF' launching, but it will be great if the Dev can eliminate de annoying start-up delay.

Thanks in advance!

非常好用，在以前FireFox內建的「分頁群組」被拿掉之後，這個tab管理套件算是很不錯的。

"HAAAaaaaaaa..." (voix d'anges avec lumière divine venant d'en haut)
Voilà ENFIN une extension remplaçant convenablement les anciens groupes d'onglets disparus avec les persona.
Que son créateur en soit béatifié !
Plus sérieusement enfin une extension qui permet ET de trier les onglets par groupe ET de cacher ceux des autres groupes.
Merci merci merci merci.
Merci.
Merci.

Works well and seems to hold and endless amount of tabs without slowing down the browser. I would have given it 5 stars if it offered a way to sort A-Z or Z-A, etc. Much better than the original Firefox version.

This is not Tab Groups. There is no functionality that I expected from an addon that claims to be inspired by it. I have found no option to skip the "groups menu" dropdown and go straight into the management screen, and further the groups management screen opens itself into a tab or a window depending on the setting you have set, yet neither of these options were the way the original Tab Groups worked. It used to be that it seemingly created a navigation bar-less fullscreen window with the tabs displayed. I don't know what the limitations of quantum's haphazardly asinine addon system are, but that's rather disappointing. I don't like the current standing separate window view, nor the tab version. Very clunky to use.

Further, although explicitly stated as being planned for a future update, you cannot freely arrange the tab groups in the grid view, which is unfortunate.

This was not worth updating from Firefox V56.0.2 for, though unfortunately I was forced into doing so by the fact that many webpages have begun to discontinue support for the legacy version of Firefox. I am left with no other choice.

Edit: Boosting up to four stars because I found an amazing workaround. You can right click > PIN the "Manage Groups" tab and then, voila, there is an always-present button you can press to bring you right to the overview screen. It's on the left, not the right, but hey it's better than being forced to use that menu.

edit:@Coconutsales:
TRY "open manage groups[STG plugin]" by Drive4ik
you can put it on the right.

Great Tab Group!
enjoy manage groups in Popup, Panorama, sidebar.
switch quickly and work well.
careful in many detail

Got so much on the go that I couldn't go back to living without this extension!

Does Simple Tab Groups supports Tab Session Manager? What should I do if FF suddenly crashes? Will Tab Session Manager restore all my tabs AND GROUPS?

It works fine in a single machine, but there is no way (at least no simple way) to make it sync between different machines automatically.

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.

Hey, thanks for making this app, it's very useful !

If you have some time, it would be nice if there was a way to move several tabs from one group to another or even merge 2 groups.

Also if you could implement a folder/file system where you can make a group of groups.

You should be able to name the tab groups and use drag-and-drop instead of going through multiple context windows. Otherwise, I'm glad I thought to look this up.

Great replacement for the old Tab Groups extensions! Wondering why is not shown as a replacement in the Tab Organizers collections along with the other ones. See https://addons.mozilla.org/en-GB/firefox/collections/4757633/tab-organizers/