Ian Winter

Logged into to Gmail this morning, as you do, to be greeted by a nice big red message flash at the top of my window:

Firebug is known to make Google Mail slow unless it is configured correctly. Fix this Hide

Clicking on the "Fix this" link takes you to a support page detailing how to make some changes aimed to improve performance.

I have to say I've not really noticed any performance issues and I have had Firebug running for some time!

[Edit]

Interestingly I've just disabled Firebug on the mail.google.com domain and reloaded my inbox and it's noticeably quicker. When I click on a conversation it loads instantly whereas with Firebug on I used to get a "loading" delay. Based on what I know Firebug does and how Gmail works it's not surprising but, it's interesting that Google are telling user's to disable it.