Unload Tabs After Inactivity от visions.ch gmbh

Unload Tabs After Inactivity keeps Firefox lean by discarding tabs that have sat unused for too long. Choose how long a tab can stay inactive, decide how often the extension scans, and protect pinned or audible tabs from being unloaded. When a tab is discarded, Firefox releases its in-memory page state. The tab stays in your window and reloads normally when you return to it.