Is it possible in Chrome or Firefox to display somewhere on the panel next to the address bar a number, how much % of CPU the site eats?

Question

Browsers

It's clear that there is a task manager, both in the browser itself and third-party utilities. But it's all in another window or in another tab.

Answer 1

Well, there is some kind of API - https://developer.chrome.com/docs/extensions/refer... Xs
is it really possible to find out for a particular site. And you can display it with a badge on the extension icon.
I googled this - https://chrome.google.com/webstore/detail/cpu-and-...
You can dig into the sources.