TabGeek: Tab Suspender by TechyGeeksHome

TabGeek frees up memory by putting the tabs you have not used for a while to sleep. A sleeping tab stays in your tab bar with its title and icon, and loads again the moment you click it.

It uses the browser's own tab sleeping, so there is no placeholder page and your history and bookmarks keep the real address. Choose how long tabs wait before they sleep, from 5 minutes to a day. Pinned tabs, tabs playing sound and sites you choose stay awake, and TabGeek can leave half-written forms alone too.

Sleep other tabs or this tab in one click or with a shortcut, and see how many tabs are asleep. No account, no tracking. Free and open source from TechyGeeksHome.

Full guide: https://techygeekshome.info/browser-extensions/tabgeek/