Adobe Flash Platform * Application frame rate

In general, use the lowest possible frame rate for better performance.

An application’s frame rate determines how much time is available for each “application code and rendering” cycle, as described in Runtime code execution fundamentals . A higher frame rate creates smoother animation. However, when animation or other visual changes aren’t happening, there is often no reason to have a high frame rate. A higher frame rate expends more CPU cycles and energy from the battery than a lower rate.

The following are some general guidelines for an appropriate default frame rate for your application:

If you are using the Flex framework, leave the starting frame rate at the default value.
If your application includes animation, an adequate frame rate is at least 20 frames per second. Anything more than 30 frames per second is often unnecessary.
If your application doesn’t include animation, a frame rate of 12 frames per second is probably sufficient.

The “lowest possible frame rate” can vary depending on the current activity of the application. See the next tip “Dynamically change the frame rate of your application” for more information.

Use a low frame rate when video is the only dynamic content in your application.

The runtime plays loaded video content at its native frame rate, regardless of the frame rate of the application. If your application has no animation or other rapidly changing visual content, using a low frame rate does not degrade the experience of the user interface.

Dynamically change the frame rate of your application.

You define the application’s initial frame rate in project or compiler settings, but the frame rate is not fixed at that value. You can change the frame rate by setting the Stage.frameRate property (or the WindowedApplication.frameRate property in Flex).

Change the frame rate according to the current needs of your application. For example, during a time when your application isn’t performing any animation, lower the frame rate. When an animated transition is about to start, raise the frame rate. Similarly, if your application is running in the background (after having lost focus), you can usually lower the frame rate even further. The user is likely to be focused on another application or task.

The following are some general guidelines to use as a starting point in determining the appropriate frame rate for different types of activities:

If you are using the Flex framework, leave the starting frame rate at the default value.
When animation is playing, set the frame rate to at least 20 frames per second. Anything more than 30 frames per second is often unnecessary.
When no animation is playing, a frame rate of 12 frames per second is probably sufficient.
Loaded video plays at its native frame rate regardless of the application frame rate. If video is the only moving content in your application, a frame rate of 12 frames per second is probably sufficient.
When the application doesn’t have input focus, a frame rate of 5 frames per second is probably sufficient.
When an AIR application is not visible, a frame rate of 2 frames per second or less is probably appropriate. For example, this guideline applies if an application is minimized. It also applies on desktop devices if the native window’s visible property is false .

For applications built in Flex, the spark.components.WindowedApplication class has built-in support for dynamically changing the application’s frame rate. The backgroundFrameRate property defines the application’s frame rate when the application isn’t active. The default value is 1, which changes the frame rate of an application built with the Spark framework to 1 frame per second. You can change the background frame rate by setting the backgroundFrameRate property. You can set the property to another value, or set it to -1 to turn off automatic frame rate throttling.

For more information on dynamically changing an application’s frame rate, see the following articles:

Reducing CPU usage in Adobe AIR (Adobe Developer Center article and sample code by Jonnie Hallman)
Writing well-behaved, efficient, AIR applications (article and sample application by Arno Gourdol)

Grant Skinner has created a frame rate throttler class. You can use this class in your applications to automatically decrease the frame rate when your application is in the background. For more information and to download the source code for the FramerateThrottler class, see Grant’s article Idle CPU Usage in Adobe AIR and Flash Player at http://gskinner.com/blog/archives/2009/05/idle_cpu_usage.html .