I found out about this extension recently. It works with browsers that can use the Google Chrome store - obviously, Chrome but also Brave. I don't know which others can.
Anyway, it reduces memory by suspending tabs you're not using. You probably don't need it unless you're using a low memory system like me (say 4 GB or less), especially if you're using shared memory with onboard graphics. As soon as you click on a tab, it becomes unsuspended. It takes maybe a quarter of a second to do so. For me, that seems to use up to 512 MB. I had 14 tabs open. It saved 400 MB of RAM by suspending the other 12 tabs. It left the last one open unsuspended because it was a pinned tab and I set it as such. You can check it out here:
https://chrome.google.com/webstore/detail/the-great-suspender-origi/ahmkjjgdligadogjedmnogbpbcpofeeo/related