Implementing Fast App Resume
Fast App Switching (FAS) is a feature that places an app in a suspended state when the user navigates away from it. The app’s state is preserved in memory. If the user returns to the app by tapping the hardware Back button or by using the task switcher, the app instance resumes. Because the app is preserved in memory, the app is returned to the same state it was when the user navigated away.
By default, if the app is suspended and the user relaunches the app by tapping on the app name in the app list or tapping the app’s primary Tile, the suspended instance of the app is terminated and a new instance of the app is created. This process is slower than resuming a suspended app.
Windows Phone 8 introduces a new feature ...