So, by mistake I had this firebug add-on installed on firefox; by mistake, because I don’t like any extensions. And it was enabled for every website. Actually, I was trying to check a bug, vulnerability : execution of arbitrary code with local privilege, which worked for an earlier version of firebug (1.01), not for the current one (1.05), i.e., the security loophole has been closed.Yay!

Now, when I opened gmail (i rarely do that!), an embedded message shows up on top, with yellow background, and tells me that firebug slows down gmail, providing a hyperlink – http://mail.google.com/support/bin/answer.py?answer=77355 – to solve the issue.

The problem is that their javascript files are so large that the firebug excuse is plain non-sense. The file size was almost 200KB (not-compressed) in the earlier version. In the newer version, I have just checked, the size is 400KB for uncompressed data, and 130 KB when compressed. That is still not sufficient to give that excuse. I agree, that for the smaller requests (like clicking on a mail to open it), firebug must be a bottleneck. But then first solve your problems, before advicing the user about others.

Related tricks

• By the way, you can detect enabled firebug using

  <script>
  var firebugEnabled =
    (window.console != null && window.console.firebug != null);
  </script>

  (may not work on local files)
  GMail also tests the same way.

• The above method will tell when firebug is enabled. To find, if user has installed the firebug extension, use this undocumented method – infact, a bug,

  <img src="chrome://firebug/skin/firebug.png" width="0px" height="0px"
   onload="javascript:foundFirebugInstalled()" />

  This works on local files as well.