This is exactly what I've been wanting! I've been fighting the Firefox memory hog for much too long, needing to close and restart Firefox multiple times per day. The built-in tab unload options didn't seem to do anything, or maybe not enough. It took me just one day using Auto Tab Discard to get in the habit of whenever I'm finished with a tab but don't want to close it, I right click on the tab, click Auto Tab Discard, and Discard Tab. That keeps my memory usage at bay. I also keep an about:unloads tab open and periodically check to see if I should manually unload a tab that I missed. Unfortunately, you can only unload from the top down, not selectively. But in combination with Auto Tab Discard, I now have no reason to abandon Firefox, which I was thinking of doing. Firefox REALLY needs to have a native way to control memory usage that actually works! (Note: I also use the Simple Tab Groups extension and keep dozens of tabs available for easy access, so Auto Tab Discard works great with Simple Tab Groups.)