Is AutoTabDiscard still helpful/necessary with whatever automatic stuff Chrome/Firefox does nowadays? I run a lot of tabs (100s-1000s) and this sounds potentially very helpful if it does something beyond what the browser automatically does.

I think Firefox will delay loading on session resume (that is, if you restart Firefox, tabs will not load until you actually switch to them),but will not unload anything automatically - so if you open 200 tabs between restarts and keep them open (which I sometimes do, for a week or two until I close them) it makes a difference.

If you toggle this it will automatically unload, thought I'm not sure how low memory has to get before it triggers: browser.tabs.unloadOnLowMemory

In my original comment above I wrongly assumed it _was_ on by default