Subset Browser Tabs
Like the possibility to switch a desktop in a browser, it would be great to have the option to make subsets of browser tabs. In other words, by switching between your stored tabs, you can go to your "social media and news tabs" subset, send some messages and when finished you go back to "christmas shopping", "next holiday" or "cooking recipes" subset.
Keeps things more organised, Firefox can save the state of all the tabs you are not viewing on your drive without using memory, more intuitive and user friendly than the bookmark system imo.
It could go where now the bookmark toolbar is. Or make it a max 10 tab sets system and just add a clickable bar with buttons of which an icon can be picked... just an idea 🙂