"Task Manager" for Firefox plugins that lists RAM load, processor use, etc...

Would it be possible to have a "task manager" in Firefox that monitors
plugins for resource usage, much like the "task manager" in windows,
so you could tell which plugins had memory leaks, etc.?

I've been using Firefox in safe mode for some time now because I'm
tired of it eating 400mb of RAM with two windows open. It'd be nice if
there were an easy way to monitor resource usage by separate "parts"
of Firefox (plugins, the browser itself, whatever)...