Windows Phone 7 Performance TipsChris KoenigSenior Developer EvangelistMicrosoft Corporation

@chriskoenig | chriskoenig.net | chris.koenig@microsoft.com

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Windows Phone

Optimizations for DirectX 9 GPUTouch, 800x480 display1 GHz ARM Scorpion

Silverlight 3

UI Threading ModelsDesktop (up to SL4, today) • UI thread

– Input – Layout + Render– Events + Binding– Animation– Rasterize

Windows Phone• UI thread

– Input– Render + Layout – Events + Binding – Some Animation– Rasterize

• Compositor thread – Basic Animation – Draw buffers

Threading ModelsUI Thread vs. Compositor Thread

Desktop to Mobile (mindset) • ~1 GHz is not that much • User expects immediacy• Network latencies are high • Small Screen = More transitions • Touch is primary input • Preserve battery life

Basic Rules of Thumb• Perceived vs. Actual Performance– How slow is slow?

• Performance vs. Complexity• Identify potential problem areas• Monitor as changes are made• Test on a device early and often• Involve designers early and often

Startup Performance Tips• Use a Splash screen• Keep assemblies small

– Partition assemblies– Include media as Content, not as Resources– Use Satellite assemblies

• Delay load assemblies • Avoid ApplicationSettings class

– Be granular, choose faster formats

• Delay load content (esp. Panorama, avoid Item parsing)

Navigating to an External Resource

private void button1_Click(object sender, RoutedEventArgs e) {

var s = "/OtherAssembly;component/ExternalPage.xaml"var uri = new Uri(uriString, UriKind.Relative); NavigationService.Navigate(uri);

}

Using LayoutUpdatedprivate bool _onNavigatedToCalled = false; public Page() {

InitializeComponent(); LayoutUpdated += new EventHandler(Page_LayoutUpdated);

} protected override void OnNavigatedTo(NavigationEventArgs e) { _onNavigatedToCalled = true; } private void Page_LayoutUpdated(object sender, EventArgs e) {

if (_onNavigatedToCalled == true) { _onNavigatedToCalled = false; Dispatcher.BeginInvoke(() => { DoWork() } );

} }

UI Performance Tips• Less is more• Minimize UI thread work• Leverage the GPU• Opacity vs. Visibility • BitmapCache• Never ever use OpacityMask• Use Manipulation Events over Mouse Events

UI - Things to Avoid• Color Animation• Non-rectangular clips• Opacity masks• Popup• Converters• Watch for Callbacks that come back to UI

thread– e.g. WebClient, GeoCoordinateWatcher, etc.

BitmapCacheCacheMode=“BitmapCache”

Useful for…• Render Transform

– Scale Transform– Rotate Transform– Translate Transform

• Change the opacity• Change the clipping

region

Danger Areas• Caches Bitmaps – not

Vectors!– You will lose fidelity– Try different

RenderAtScale

• Items frequently redrawn

• Non-rectangular clips

Performance Counters• Composition Thread FPS• UI Thread FPS• Texture Memory Usage• Surface Counter• Intermediate Surface Counter• Screen Fill Rate Counter

UI Performance

BitmapCacheFillRateTest

ListBox Performance Tips• Don’t load so darn much data!• Simplify ListBox ItemTemplate• Avoid converters on bindings • Load images in the background (LowProfileImageLoader)

• Use Data Virtualization (e.g. LazyListBox)

• ListBox alternatives– StackPanel for short lists– LongListSelector for complex lists– LazyListBox + LowProfileImageLoader for alt. templates

Control Alternatives• PerformanceProgressBar• LowProfileImageLoader• LongListSelector• LazyListBox• DeferredLoadListBox• DeferredLoadStackPanel • GroupingItemsControlConverter

Custom ControlsPerformanceProgressBarLowProfileImageLoaderLazyLoadListBoxVirtualizingDataTest

Data Performance Tips• Consider network latency• Consider impact of holding data in

memory• Parallelize data requests to save battery• Process data on background threads*• Use HttpWebRequest instead of WebClient

Media• Use Jpeg over Png whenever possible• Use Images over Xaml whenever

possible• Limit image size to 2K x 2K• Set Build Action to Content• Encode media for optimal playback rate

and resolution

Fast is not good enough!! • Perceived performance is important!

– Feedback on clicks – ProgressBar (use Jeff Wilcox) – Transitions across pages

• That said,– Don’t rely on our magic. – Use the counters and flags to verify. – Balance ‘feedback’ with real work ...

Summary• How slow is slow?• Plan ahead for problem areas• Utilize the counters• Test, test, test – especially on a

device

chriskoenig.net/WP7Resources

Thanks to Jaime Rodriguez, Yochai Kiriati, Jeff Wilcox, Peter Torr and all the other great presenters, speakers and bloggers from whom I found all this great content about performance tuning Silverlight applications for Windows Phone 7.

Credits