It lets you unload all tabs to save RAM and resources in general
All it does is wait for you to click on the extension's button or the extension's shortcut and it will unload all tabs other than the one you currently have open
You can change your shortcut at URL about:addons 1. Find the settings cogwheel next to "Manage Your Extensions" 2. Select Manage Extension Shortcuts 3. Find Unload Tabs and customize the shortcut
