Performance advisor (part of Operations Manager) can do it. There are (now web-based) tools that would produce pretty graphs from performance archives or perfstat results, available to NetApp employees or partners; you could ask your NetApp representative to help with it. Finally, there are free solutions based on widely available monitoring tools like Cacti or Nagios; you will need to spend some time to set them up and collect data (although it is possible to preload RRD tables with historical data using some script magic).
But if you have performance issues, it makes sense to open call with NetApp anyway,