Because I don’t have a device to use in order to test my Windows Phone 7 application and the emulator cannot emulate performance, I found a great session at Tech-Ed with the best practices in order to get better performance in your apps. Then I applied where I learned there to my code and use the emulator. This are the tips I got, let’s share it with the world, when the devices start coming into the market you don’t want to find out your application performs badly on those devices. I personally like to test it on a Intel Atom Netbook computer, if performs good there, I can assume that will perform well on the ARMS processor.

To enable the Performance counter you need to use

Application.Current.Host.Settings.EnableFrameRateCounter = true

Should be 60 frames per second, this are the counters to keep an eye at:

• Render Thread frame rate
• UI Thread frame rate
• Amount of VRAM used by App
• Total # of Textures on GPU
• # of Intermediates

To enable the Dirty Regions counters.

Application.Current.Host.Settings.EnableRedrawRegions = true;

Practices to drive performance for Windows Phone 7

• Indentify potential problem areas
  • Startup, memory, framerate
• Monitor as changes are made
  • Framerate, size of Dirty Regions
• Less is more
  • Slim Visual Trees
  • Collapse items that are not visible
    • Z order doesn’t count
  • Avoid small property changes or use the render thread animation.
• Minimize UI thread work
• Leverage Off threads
• Leverage GPU
  • Use simple animations of Simple properties
  • Cache
  • Avoid large textures
• Caching
  • CacheMode = BitmapCache will cache the rasterized version of a UIElement and its children
  • Silverlight auto-caches animation when possible, Don’t count on it, verify it.

Media

• Video (MediaElement)
  • Rendered in Render thread
  • Must be cached. CacheMode required in earlier builds, not required later, but it is being applied.
  • Still, less is more:
    • Right size
    • Minimum frame rate possible.
• Images
  • Decode in Software

Start Up

• Use a splash screen
  • include applicationsplashscreen.jpg
• Delay loading resource at start-up only and load other resources when needed.

When submitting into the market place one of the things that you going to check is starting time. So make sure your application starts fast, try to avoid including many resources on your application, just download the as needed.

Performance pitfalls

• SW-only features
  • Non rectangular clips
  • Opacity mask do not use it.

Hope you keep in mind all those while you writing code, I’m doing the same thing for all my WP7 development.

Cheers

Al