Workona - A better way to work in the browser.
Auto Tab Discard - Auto Tab Discard a lightweight extension that uses the native method (tabs.
OneTab - Whenever you find yourself with too many tabs, click the OneTab icon to convert all of your tabs into a list. When you need to access the tabs again, you can either restore them individually or all at once.
Firemin - Firemin will force Firefox to use less memory. It is safe to use, spyware free and completely free.
Session Buddy - Manage Your Browser Sessions
Total Suspender - Total Suspender is a platform that comes as an extension for the Firefox browser to suspend the processes of tabs.