There are extensions that can search the body of the open but out of view tabs.

I have commented at length why I use so many open tabs. Basically that's my cache-to-do-list. Once I revisit certain tabs enough times they get upgraded to a bookmark. What bookmarks don't do well but tabs do marvelously is preserve the trajectory and context of how I arrived at the page. Very useful to recreate the state when I visit it later.