I've switched back to Firefox from Chrome and on the hunt for equivalent extensions.

This is basically the only memory-saving extension per tab while OneTab puts all tabs open into one—I can whitelist/blacklist but lazy here.

This extension is minimal, but it works. Thank you.

If you can get this extension on par with The Great Suspender on Chrome, that would be awesome but not necessary.
Also, I agree with Firefox user 14753074.