Firebug 1.9b3 has been released (compatible with Firefox 5-11.0a1).
See AMO archive for all Firebug final and beta releases.
Firebug 1.9b3 fixes 10 issues.
Try it out and let us know how it works for you!
We are also still hard working on reducing amount of memory Firebug needs and we appreciate any specific test cases that shows when exactly is Firebug consuming too much memory.
Post feedback in the newsgroup, thanks!
Jan ‘Honza’ Odvarko