New home page & tab page
A new default home page giving quick access to bookmarks, history, settings and more. Ubuntu 12.04 users won't be getting it, though. We're still on the old home page that comes with Ubuntu's Firefox.
At least, the new tab page is available for everyone not just Windows & Mac users.
SPDY on by default
Google, and any other website that supports SPDY will get a healthy boost of speed now that the new SPDY protocol is turned on by default. Of course, if you've already turned it on manually in previous Firefox releases it'd make no difference.
On-demand tab loading
Background tabs don't load to help speed up Firefox startup. If, like me, you don't save sessions with loads of tabs then this probably wouldn't impact your experience in any way.
Ubuntu users should already be able to update to Firefox 13. Just fire up Update Manager and update the cache. It should be ready for download.
|You can already update to Firefox 13 through Update Manager.|
Check out the detailed release notes for more info.