I've been trying to live with it for a while, and decided it was time to ask the community.
Ever since Firebug 2.0, I've found Firebug to be considerably slower when loading, occasionally not stopping at breakpoints I set in code (same breakpoints work in the debuggers of the other browsers), and slowing my application to a halt. This does not happen with the other browsers. Because of this, I used Firebug 1.x until it no longer supported the version of Firefox I've used.
I'm a long time Firebug user and have had to switch to Google Chrome because of the performance and issues with Firebug 2.x. I've tried 2.0-2.07 and see the same problems.
We are using Telerik Kendo which does seem to have something to do with it, but this was never a problem until 2.x.
I know there isn't much info here, but I don't know what to give. Feel free to ask and I'll try to give examples.