Windows® Phone 8 Unleashed

The Threading Model for XAML-Based Graphics and Animation in Windows Phone

XAML apps use two threads for graphics and animation: a UI thread and a composition thread. The composition thread was introduced with the second release (7.5) of the Windows Phone OS. The first release of the OS had issues with performance around user input. A single UI thread had been largely acceptable for Silverlight for the desktop and browser because both generally rely on the mouse for input. The phone, however, relies on touch, which, as it turned out, needs to be substantially more reactive to user input. When using a mouse, a slight delay does not unduly affect the user’s perception of your app, but when using touch, a slight delay can make the user feel like ...