How to easily Check Firefox Memory Usage
To avoid this and make your firefox run smooth and fast there is an option in firefox which allows you to check which add-ons are eating up your memory. However this option is not all that user friendly and requires some bit of 'how to' knowledge to understand.
To get access to your memory in a more efficient and user friendly manner you will need to install another add on to help you, just go over to about: addons-memory download and install.
Note: The add-on memory app will work best with the latest version of firefox.