If you have built a Windows 8 app, you are probably familiar with the WACK (Windows App Certification Kit). This small utility allows a developer to make sure that their app passes the basic tests performed during the Windows Store certification process. Visual Studio 2012 advises you to run the WACK each time you create an app package. This tool is great for small and simple apps, but for more complex ones you will need a better way to evaluate their performance. That is why you should also test using the Performance Analyzer for HTML5 Apps.