I thought there was a way to view what plugins were contributing to the performance meter, allowing you to see which ones were using the most processing power. Can’t seem to find it now. Does such a view/device/window exist?
No 
Its something I’d really like to see in Cubase, but it doesn’t do that at the moment. Perhaps you’re thinking of ProTools, their feature is very informative when up against processing power!
Also memory usage would probably pretty good as well 
Mike.