Bookmarks, tabs, pinned tabs, etc. all sit at different places on the same continuous spectrum of UIs for saving web pages for later. Once you implement unloading of background tabs (which you can in FF via add-ons), they can start to look a lot like bookmarks.
You don't need to use an add-on (anymore?) for keeping them unloaded, although you do need one to get a more manageable user interface. When you have more than about 1000 tabs, startup end closedown get rather slow though.
> although you do need one to get a more manageable user interface
I know this get mentioned every time there's a discussion on Firefox UI and extension, but Tree Style Tabs [ https://addons.mozilla.org/en-US/firefox/addon/tree-style-ta... ] is one excellent example of such extension.
For Chrome, there is this great extension called "Tabs Outliner". Gets work done really great! Pity that after so much time there is no FF equivalent...
