responses Rated 5 out of 5 stars
@J03P: you don't need to disable sites in firebug 1.2, because in this version everything that costs speed (network analysis, etc) is by default not activated. And the DOM tree is constructed only when you click the firebug icon.
@sickearth: it seems that those days, the website getfirebug.com does not resolve (there's no DNS). So as soon as Firefox will search for updates, it will freeze... so until it's fixed, I suggest everyone to turn off the automatic update for extensions (in "options" window, "advanced" icon, in the "update" tab).