It's great when it comes to keeping tabs neatly arranged on a smaller scale, however, it doesn't manage large numbers of tabs (500+) and containers (8) well, especially when combined with multiple windows. With multiple windows the containers become routinely reset (all tabs are moved to the default container) and the add-on confuses placement of some tabs. Pinned tabs become routinely unpinned and I have also lost the configuration of containers several times now, which is a shame because I loved using the simple automation and integration with firefox containers this add-on offers. It is in my opinion a perfect tabs manager when it comes to the features, hovewer the performance is lacking.