I think it would be a great idea to add a feature similar to the task/process manager in Windows, to Sonar.  The Performance meter is great for giving users an idea that something may be using too many resources, but it really doesn't help pin down what is using those resources.  Having the ability to double click the performance meter, and calling up another window which breaks down exactly what % of resources, ie.  cpu, memory, HD, that each plugin, synth, ect is using, would be a great addition.