It seemed that a progress bar component was the issue.
In the application the progress bar was wrapped in a vbox, which was part of a viewstack.
Switching from the view with the progress bar to the other caused the AIR app to consume CPU.
Sorry it took so long for us to get back to you. I haven't seen this myself but I'm very interested in trying to reproduce the problem. Would it be possible to get sample code that I could use to reproduce this on our side? Please feel free to email me at firstname.lastname@example.org.
Do you think the 100% cpu usage could be due to the native app? Have you tried listening for NativeProcessExitEvent.EXIT to see if the process really quit as expected?
Oops, looks like you posted while I was composing a reply. I'm glad you were able to sort out the issue, but I'm concerned that this might still be an AIR issue. What's your take?