When Microsoft shipped the Mango tools for Visual Studio they included Windows Phone Performance Analysis Toolset. This is a memory and cpu profiler specifically developed for Windows Phone 7.
The original docs were IMHO atrocious, really unhelpful. However in the last few months there have been some great articles explaining how to really user the tool and more importantly understand and navigate its output
My 3 favourites are
- Memory Profiling for Application Performance
- How to: Identify and Fix Common Performance Issues Using Windows Phone Performance Analysis
- How to: Capture and Analyze Performance Data Using Windows Phone Performance Analysis