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I have an html5 video app which consists of video + JS swipable playlist + other JS animated overlays.

In iOS, onload performance of the playlist swiping and overlay animation is fine. Once a video has played, even if it is stopped, the playlist swiping and overlay animation is very very slow. Some users think it is not responding at all.

In Chrome/desktop, everything is fine.

If I log status information, the logs look the same regardless of whether a video has played or not. I don't know where to begin to debug. It seems to be a memory issue (?), but not sure how or if it can be addressed.

Anyone have any thoughts?

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Are there any iOS-specific JS performance enhancement techniques? –  reader Feb 4 '11 at 14:57
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Javascript in iOS (both safari and UIWebView) execution can be stopped (or killed could be more appropriate term) without throwing any errors if under heavy CPU load to save more power for background native tasks or special tasks like handling video - rendering video even if hardware (GPU) supported still requires more CPU power thus it gets higher priority then javascript and can lead to the javascript acting not as intended or expected - it can work sluggish or not at all in extreme cases.

The only thing I can come with is pausing the video on any user input in iOS - maybe it would help.

regards, Tom

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