It is very easy to remove Certificate exception from firefox.
Just click on Tools>>Options>>Advanced >> Encryption >> View Certificates
A new tab will option
Click on "servers" tab
There you can select certificate and click "Delete" button
Here are some screen...
I just read an article by "Chris Morrell" about optimizing Firefox. He explained very simple way to tweak and optimize firefox, you can read it by clicking here.
Firefox extensions are small add-ons that add new functionality to Mozilla applications. They can add anything from a toolbar button to a completely new feature. They allow the application to be customized to fit the personal needs of each user if they need additional features, while minimizing the...