I do not remember which version introduced the current interface for bookmarking tabs, but as a user who organises their bookmarks in folders, I find it slow and overly complicated and would be interested to hear if other users find the same?
The particular issue I have with bookmarking is the "Location" option, which by default only shows the bookmark folder which was last selected, and then the drop down menu only shows the options "Bookmarks Menu, Bookmarks Toolbar, Other bookmarks" and recently used folders.
This means that to chose a folder which is not recently used, you have to select "Chose" before your full folder list is displayed.
Historically, you could expand the locations list with one click and see the full folder list.
I can understand that the current arrangement must have been considered an improvement for some reason, but it would be nice if this behaviour of using recent folders instead of just presenting a folder list could optionally be disabled in the Firefox configuration.