I don't know if you're familiar with the ins and outs of writing computer programs, but it's actually often practical to make a program that does one thing do another instead. So in this case one obvious thing that could be done is to have a dormant-type (exact terminology TBC) tab.

Such things would have an entry on the tab bar like a normal tab, but wouldn't actually have anything loaded until you clicked. Firefox already supports this sort of thing internally, it looks like, since when you reload a session that had a bunch of open tabs, it doesn't seem to load each tab's contents until you click on it.

(Open such a thing with a particular shortcut, or by transforming an existing tab into a dormant one - obviously equivalent in terms of JS callbacks and so on to closing the window.)

Other possibilities could include multiple types of tabs, and/or alternative UIs for lists of pages you like/pages you want to look at sometime soon.

Now we know how people behave we can engineer the software to work well for them. Suspend the LRU tabs so they can be paged out, etc.