GMail, Thank You For Your Help
I logged on to GMail today (in Firefox) and observed a message indicating my experience might be slower due to Firebug being enabled.
What I enjoyed about my experience is that the GMail team did not stop there. After following a "fix it" link I was brought to the following set of directions:
Then I received confirmation that the Firebug would not hinder my GMail experience:
I enjoy using applications that take the initiative to solve problems I may not have even known about. I think this is an excellent example of improving UX.