Not a big fan of this. I live and die by my tab groups, so when Firefox did away with them, I needed a replacement, so I downloaded this. After using it for about a week, I dont like it and am looking for a replacement. Why? There are numerous problems with it. Where do I start?
It forgets what pages you had loaded in some tabs
It duplicates not just tabs, but entire groups of tabs
If in tab manager, you delete one tab, it takes you to the top of that group of tabs immediately

But the biggest problem I have with it is this: every time you open the browser or switch between tab groups, it insists on loading every single tab in that groups. Did I mention when I first opened my browser with this installed it put all my tabs from all groups into one group? Yeah, it does that. So I had about 160 tabs and it insisted on loading every one of those pages all at the same time. I've been working to cut back and separate tabs into groups, but I still have maybe 75 tabs in the largest group, and I don't see any improvement in performance. I recommend downloading it because Firefox has screwed us over and this is the only game in town as far as a solution. But before you install it, I recommend minimizing the number of tabs as much as possible.