But use of FireBug add-on in Firefox may slow down GMail performance. In order to solve this GMail loading issue, you have to configure the FireBug add-on such that FireBug can be disabled for GMail alone.
Follow the steps below to disable FireBug for mail.google.com
Login to to GMail.com
Click on the red or green icon at the right bottom corner of FireBug enabled Firefox browser.
Click on the FireBug icon and select Disable FireBug for mail.google.com
Done. But if you still want to debug, then you can customize the Firebug by clicking on the Options in the FireBug tool bar and disabling the showing of errors in different categories.
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