Auto-close unused Firefox tabs with Dustman
You can resize Firefox tabs, group them, send them to another window, but it won’t make any difference: there’s never quite enough tab space to go around. Dustman is a free Firefox extension which helps out by automatically closing tabs which haven’t been used in the last 20 minutes.
That could be potentially risky, but as with the similar Tab Wrangler for Chrome, the developer has used several tricks to reduce the chance of problems.
Dustman won’t close anything you haven’t viewed yet, for instance, and it won’t close tabs if you’ve got a few open (less than 5, by default).
Pinned tabs are also ignored.
If you still lose something important, clicking the Dustman icon displays a panel with up to the last 100 closed tabs -- just select whatever you need to restore it.
All these figures and settings may be tweaked, enabled or disabled in Dustman’s Options dialog.
If it still causes issues in some situations, you can temporarily disable the extension in a couple of clicks.
Dustman is a free extension for Firefox.