Dormancy 'retires' tabs that have gone unused for a while, freeing up that memory. It then restores the tabs to life when accessed.
Tabs are considered inactive when they haven't been selected in longer than 5 minutes.
Tabs are checked for inactivity every 5 minutes.
Click the [d] icon on your browser toolbar to change the default to more or less than 5 minutes.
File issues and request features at https://github.com/autonome/Dormancy.
Note: Your form data should not be lost. This extension uses underlying Firefox APIs to save/restore the tabs, and those APIs handle form data. If you're seeing form data lost, please file a bug for Firefox: https://bugzilla.mozilla.org/enter_bug.cgi?product=Firefox