SaveMemory can reduce Firefox's memory and CPU use by more than 80%!! If you browse with multiple tabs, you need SaveMemory. It lets you pause unused tabs to free up memory and end unnecessary processor usage. It makes Firefox faster and snappier!
SaveMemory adds a pause button to every tab that will remove it from memory but leave the tab open. There are also menu items for 'Pause All Tabs' and the extremely useful 'Pause All Tabs and Restart'.