Monitoring Performance in a Silverlight 2.0 Application

While there is no perfect answer for full power profiling, convert your Silverlight app to a WPF desktop app. There are many profilers for WPF desktop applications.

Alternatively, I found a pretty cool tool that might suit your needs: Silverlight Spy is a free base profiler for 2.0 and 3.0

This article explains some of the other approaches that users have taken

This Stack Overflow question gives a different answer using Windows Server tools, but it doesn't mention these other methods and I'm not sure if you are asking the same. This assumes the use of XPerf anyway, so here's a great explanation of Silverlight profiling using XPerf