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Could you elaborate? It would seem performance issues would be tied to whatever Angular code is being written. Or are there UI issues?
Initially, we focused on iOS only just to get the alpha out in November. Turns out demand for Android was huge, but we were doing things that worked well on iOS (like box-shadow) and certain animations, but hurt Android performance on sub 4.4 devices. We've since built a system to gracefully fall back to less intensive operations on older Androids, and we have made a good amount of progress on Android performance ove…
http://developer.android.com/about/dashboards/index.html
I agree with you on box-shadows -- its a big no-no in the android-land. There are some things however android chrome does better than mobile safari, batching browser repaints for instance. If you focus on CSS-driven animations/interactions for your ui, you should be able to reduce the performance issues on android though.