I' m using Firefox 111, and I discovered it has active a fantastic option.
You can open 20 tabs and it runs faster because Firefox does not activate these inactive pages till you click on them.
As an example, you can click with your mouse wheel 10 youtube videos, to open each one in one tab.
Previous FF versions charge them at the same time so a bottleneck appears.
Now they solved this and you can browse faster.
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N.b when using previous versions of FF, YOU can obtain this functionality by...
Type "about:config" in the Firefox address bar and press Enter.
Click the "Accept the Risk and Continue" button.
In the search bar at the top of the page, type "browser.tabs.loadOnNewTab" and press Enter.
Double-click the "browser.tabs.loadOnNewTab" preference to change its value from "true" to "false".
Once you've done this, Firefox will no longer load tabs until you actually click on them to open them. Instead, a blank page will be displayed until you click on a tab to open it. This can help improve performance, especially if you have a lot of tabs open at once.
I hope this helps!