Since WPF was released it has seen a fairly rapid adoption but not much in the way of guidance. The WPF team at Microsoft is hoping to change that with the release of the WPF Application Quality Guide. The guide is going to be released in stages and will be updated based on feedback provided by the community. While the first release is still missing a lot, it does provide some good tips on setting up your application for automated testing.
They also provide a good list of tools for performance profiling:
Using Performance Profiling Tools for WPF. Event Trace. Use this tool for analyzing events and generating event log files. Perforator. Use this tool for analyzing rendering behavior. ETW Trace Viewer. Use this tool to record, display, and browse Event Tracing for Windows (ETW) log files in a WPF user-interface format. Visual Profiler. Use this tool for profiling the use of WPF services, such as layout and event handling, by elements in the visual tree. Working Set Analyzer. Use this tool for analyzing the working set characteristics of your application.