Sites and tab groups can now have a timeout of their own instead of only being exempt. Pick anything from 5 minutes to a week, or Never. Groups left on Default follow the main timing, and Zen folders are tab groups, so they work here too.

The main timing now uses that same list of choices, replacing the number field and unit buttons. "Only unload when I ask" moved into the list.

Tab rows now show the site under the title, because a title alone often does not say which site it is.

Unloads tabs you have not touched in a while, so a browser holding dozens of tabs stops costing dozens of tabs' worth of memory. Tabs stay in the tab strip and reload when you return, with scroll position and anything you typed still there.

Keep-loaded lists for individual sites and for whole tab groups, a toolbar badge counting the tabs still using memory, right-click items and keyboard shortcuts.

Desktop Firefox only. Firefox for Android is not supported, because the tabs.discard API is not available there.