I have been looking for a replacement for Tab Groups and this is promising.

However, I have a lot of pages that I refer to, my hope is that someday the developer(s) will add the functionality to open one group at a time so that I don't have to load all them into memory at once. Ideally I would like to start Firefox with no open group then have the ability of opening a group and when shifting to another group all of the tabs I had open would save and close and the chosen group open all tabs. In other words each group of tabs could be loaded separately.