Analyze the performance of your JavaScript Windows Store app

Applications published in the Windows Store must be fast and fluid, otherwise they won’t pass the certification because of the following requirement:

3.8 Your app must meet the basic performance criteria on a low-power computer
The app must launch in 5 seconds or less
The app must suspend in 2 seconds or less

Unfortunately the Windows Application Certification Kit is not enough the thoroughly test this requirement, because that tool runs only a few performance test. To test your JavaScript app, you can use the Performance Analyzer for HTML5 Apps tool from the Windows 8 SDK. After you install Visual Studio, this tool will be installed as well, but it won’t appear on the Start screen, so you have to start appperfanalyzer_js.exe manually from the C:\Program Files\Windows Kits\8.0\bin\<platform>\AppPerfAnalyzer folder.

This is the beautiful (?), modern (?) UI of the app (to get the full experience, click the image to see it in the original size):


Use the Please select an app to analyze to select your (or Microsoft’s Mosolygó arc) app, then click Let’s get started to start the analysis. By clicking the Advanced button, you can customize which tests you want to run:


The tool guides you through an 8-step wizard, giving you detailed instructions in every step:


You should take the given times seriously, otherwise the Analyzer won’t be able to collect enough data to analyze your app. The result is a HTML report with numbers and charts, which you can find in the C:\Users\<username>\AppData\Local\Microsoft\HTML5AppAnalyzer\Traces folder.

The following features of your app are analyzed:

  • Activation time
  • UI responsivemess
  • Layout passes
  • Synchronous XMLHttpRequest on UI thread
  • Image scaling
  • Memory footprint
  • Runtimer broker memory reference set
  • Memory leaks
  • Idle state CPU usage
  • Successful suspend
  • Memory reduction when suspended
  • App memory growth
  • Runtime broker memory growth

By using the HTML5 App Analyzer, you can learn a lot about the performance of your app, so you can occasionally run his tool regardless of the certification process. You can find performance best practices for JavaScript Windows Store apps here:


4 thoughts on “Analyze the performance of your JavaScript Windows Store app

  1. Rickdg

    Hey György, I was watching a video on how to do a JavaScript Windows Store app and i want to know if I can add a Windows Store app to an existing 4.0 Web Forms app? I can’t develop in VS 2012 but I think it would be cool to use this newer technology, at least to stay current. So what I am asking is can you take all the dependent javascript files and css files and the default.aspx file add it to a 4.0 app, or is there other forces going on that prevent this magic from happening? Thanks for your posts, Rick

    1. Balássy György Post author

      Hello Rick,

      The answer is it depends. You can imagine a Windows Store app as a client side of a web app that runs only in the browser. If you use classic language elements from HTML, CSS and JavaScript you can definitely move between a Windows Store app and a web app. If you use the WinJS controls or any features of WinJS or WinRT, then your code will run only in a Windows Store app on Windows 8.
      You have much better chance for success if you move code from a web app to a Windows Store app, than in the other direction. In a Windows Store app you will probably use some Windows 8 features that you cannot do in a webapp.

      Hope this helps.

  2. Pingback: WOWZAPP preparation materials « Codes from the field

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