Tab Manager by Lakshay

Tab Manager is a Firefox browser extension that helps users save, manage, and reopen tabs to reduce memory usage. It is especially useful when multiple tabs (e.g. 30–50) are open, causing high memory consumption and slowing down the system.
With this extension, users can:

Save tabs without leaving them open.
Close saved tabs to free memory.
Reopen saved tabs at any time, even after a restart.
See visual status updates of tabs (saved, removed, opened).