Even though I have 16 GB of memory, Firefox sometimes eats up lots of it and/or lots of CPU when I have many windows and tabs open.
It's impossible to find the high consuming tabs. Give us a command or display to identify which tabs are the highest resource hogs.
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While there is nothing as easy as what you're describing, Firefox now has a "Power" profiler that allows you to record the activity of a tab and understand its Power usage:
Make sure if you enable this to select the "Power" setting.
There is an internal page with the address about:processes that -- at least on Windows -- allows you to see Memory and CPU usage per process, and lists which tabs are in that process. Starting in Firefox 108, Shift+Esc opens that internal page.