I consider this to be a mandatory to use addon.
If you have lots of tabs, Firefox does not have any automatic way of preventing them from being loaded forever, eating RAM in the background, and this is where this addon helps greatly.

Great addon; useful and efficient.

To the developer:
Could you make the favicons dimmer when a tab is discarded? sometimes I forget which tabs are unloaded and end up loading them by mistake.

Is it possible to automatically discard non-active tabs when a certain amount of RAM is being used?

Thanks for the addon. It's a lifesaver.

Greatly reduce my Firefox memory usage, and prevent tabs automatically reloading when opening the browser.

Perfect, other than it doesn't keep the tabs favicon.

Works well but when I reopen firefox I lose pinned pages and i have crash when play videos in full screen, some lag and finally when I come out of full screen crash the tab of firefox

Switched to this from Tab Suspender. Needed something that would work with the Tree Tab (Kroppy) session export feature. This extension does the job perfectly.

I really like this add on, but I've noticed recently that I am losing the URLs of some tabs that have been discarded. I suspect the URLs that are disappearing are tabs that I have not yet switched to but I havent tested this yet.

It makes FF usable again - without it FF eats a lot of CPU/Memory if you have many tabs

This does not work with F58 but if you read the description you will know this works with F59, which is currently in alpha. Use F59 if you want this.

Love it! Much smoother than the non-native extension. One thing though: can you implement sync for settings and exceptions whitelist?

Great addon. It doesn't seem to discard tabs with forms, though, even if I configure it to do so, and even if the forms have no new text input (i.e. any random page with a search box isn't unloaded).

Thank you for implementing my suggestions. The addon is great.