Sudden drop in iPad AIR application performance with renderMode = GPU

Question

We have an AIR application running on an Apple iPad that sometimes experiences a sudden drop in its performance. The frame rate drops from 60 frames per second to 2 frames per second and is never restored.

Some of our observations:

• it only plays on iOS 4, but never on iOS 5 - we checked that on two identical iPads (generation 1)
• performance sometimes drops, but it always happens when we switch between applications - from our application to another and vice versa
• very rarely, performance degradation also occurs when you first start the application
• a performance issue does not occur in renderMode=CPU , but this mode does not work for us because rendering is ugly, especially on rotated bitmaps

Has anyone else encountered similar problems? Any ideas how to deal with it?

Answer 1

This sounds like an AIR runtime error when rendering the GPU, as it only happens on iOS 4, not iOS 5. However, it is possible that your iOS 4 device has too little internal GPU memory to store all cached conversions. After your cache will be full, you will see a huge drop in performance (perhaps the same drop in your vision). You should use object aggregation as much as possible to minimize cached conversions.