The Reason Firefox is My Default Browser! Rated 5 out of 5 stars
This add-on is the main reason that Firefox is my default browser. It is hard to believe Firefox did not incorporate this functionality into their browser long ago.
If you are like me and routinely have more than 20 or so tabs open at once (actually I commonly have a hundred or more open at once), this is a must have app. I have it configured to display tabs on the left side of the browser since with my typical widescreen laptop monitor I always have plenty of horizontal real estate on the screen.
Tree Style Tabs lets me scroll through my 100+ tabs as quickly as I can move the scroll slider with my mouse. An absolutely amazing add-on.
I began using Tree Style Tabs with FF4 and Vista 32-bit running with 4 GB RAM (3.25 accessible). Back then my Firefox would crash maybe once every three days or so and I attribute this to simply taxing the resources too heavily with dozens and dozens of open tabs.
Now I'm running Windows 7 64-bit with 8 GB of RAM and Firefox with almost 200 tabs open is almost perfectly stable and fast as ever. Maybe every other week it'll crash on me (if that), but I could care less. Having this functionality for a bi-weekly crash is well worth it, especially since Tree Style Tab works so well with Session Manager to quickly restore a previously crashed session.
BTW, when restoring such a large session (200 tabs), Tree Style Tab with Firefox 14 is very fast as the page titles for all the tabs all load almost instantly. The contents of individual web will only load once they are clicked on in the tab tree. Five stars!