Literally perfect, way back tried some other equivalent (probably "Auto Tab Discard" or that's at least close) and always had weird issues, as if discarded tabs were still causing massive slowdown and eventually crashes. Same with the identical functionality included in SideBery.

Haven't had any problems with this one yet. I was able to keep browsing comfortably with 3000 tabs without quitting FF for about 20 hours. Using the alternatives would have made the browser choke and die at ~1000.

A neat feature addition would be a configurable minimum amount of open tabs before tab discarding kicks in.

Funktioniert gut und tut was es soll. Mein Speicher wird nicht mit ungenutzten Tabs vollgemüllt!!! Mein Rechner ist nun weider flott.
Danke für die App!

Unfortunately, for me, it's not doing anything. I have it set for 30 minutes. I just unlocked my computer after having been on all night and all of my tabs are active.
MacOS 10.15.7, Firefox 81.0
I would have preferred to put this in a bug report rather than a review, but I don't see a way to do that.

<3 :P :B ;D *** REQUESTS PLEASE! *** ;D :B :P <3
#1. OPEN TAB IN DISCARDED TAB IN CONTEXT MENU! :D
#2. EXCLUDE PINNED TABS OPTION! (ON/OFF)
#3. RESTORE HIBERNATED TAB ONLY AFTER CLICKING BUTTON (LIKE 'GREAT SUSPENDER' IN CHROME).
#4. DISABLE/ENABLE AUTO DISCARD FEATURE!
#5. INVERT WHITELIST OPTION! i.e. ONLY DISCARD THESE DOMAINS...
#6. PLEASE COPY FEATURES FROM "THE GREAT SUSPENDER" @ CHROME :D

A fantastic add-on for everone who occasionally has to use many tabs for certain research work, but easily runs out of memory.
Two suggestions for the designer that would make a enormous improvement:
1. It'd be good to have an easily accessable switch in the button bar for quickly toggling between on and off. I now have to use the add-on menu to manually activate and deactivate this add-on pedending on the specific task. And I have to toggle more than 20 times a day!
2. Instead of having a white-list for pages where 'Discard' doesn't work, it would be good to have an option for entering a list of pages for which discard is active. As for me, it is mainly one address only for which I need an automatic discard.

This extension works flawlessly! The only problem is that there is no option to keep pinned tabs open, and that would be an amazing feature. An even better option would be to allow certain tabs to remain loaded by clicking some option on them. Overall, a great and lightweight plugin though!