At least in Reaper's case, it's just a list with individual CPU hits per plugin. Assuming this is what the OP is looking for in SONAR, it would be up to the user to determine which plug-ins would be good candidates for freezing or bouncing to free up the necessary resources. Now it's trial and error based on what the user thinks he/she can afford to freeze, and gauging the success or ineffectiveness versus the main CPU meter.
Makes a lot of sense to me personally, and would likely be most valuable to those with marginal DAW's (mine) and those who use a lot of soft-synths (me too).