I've been using this only for a few days as a possible replacement for "Tree Style Tabs" (which loads slow). I like it and it reminds me of the the old Tab Tree extension with new abilities. I like the groups idea. But I guess I'm a bit confused as to why both groups and folders, since they perform the same function (from what I've seen), except one is vertical and the other horizontal.

I'm giving it three stars for two reasons (and would happily update if these issues were addressed):
1. Ctrl-W (close tab) not only closes the tab, but jumps you to the last group in the list. It should close the tab and not only remain in the same group, but go to the previous tab.
2. There is no way to contact the developer from the Options screen (only links to donate).

[UPDATE 1] Tabs load instantly, which is awesome. Ctrl-W *does* close a tab and return to the previous or next-up tab ((+1 star)). Groups are awesome, esp since I can keep an eye on the number of tabs! Tab unloading is great, but I wish the pinned tabs wouldn't unload. But the reload time isn't too painful. Still no way to contact author from the Options screen.

[UPDATE 2] Groups all of a sudden disappeared upon browser update and restart. Tabs are still there, but now they are all in the Ungrouped default group. Browser updated to 62.0.2.