In Firefox I have A LOT of bookmarks (thousands, accumulated over the years) and the performance of this add-on is more than bad.

If I want to move some bookmarks to a newly created folder, if I'm lucky with just one bookmark it takes three to four seconds, but with multiple bookmarks (even half a dozen) the time is absurdly long.
To the point that I can't even understand if he has accepted the command or not, also because there is no visual feedback of the fact that it is working.
In fact, in many cases it does NOT accept the command, not even for a single bookmark to be moved!

Now, I understand that I may even have an "excessive" number of bookmarks, but other add-ons that allow me to move a single bookmark, with drag-and-drop, are still much faster and always work.
Unfortunately, my need (and certainly not mine alone) is above all to have a tool that allows you to do "group" operations on bookmarks and this add-on, which on paper would be what it takes, in practice fails too often the task .

The idea is excellent and responds to a real and great need, but at the moment the implementation is so poor that in my case it is almost unusable.
Too bad, I hope for a next performance improvement (the graphics should also be improved a lot, but in the first place it is the performance that should be fixed).