kmsravindra
The bulk of these issues are related to hardware limitations. Positioned is doing its job, its not meant to rescale dynamically, and your issues may be related to what fullscreen mode your project is using, and if high quality is enabled etc.. Most of your issues would be solved by behind mode with autofit, any reason you arent using it? You need to make the layers transparent for it to be visible so no c2 background is rendered.
I cant improve the performance of inside mode, it is upto a browser how efficient it will be, and infact is badly supported on anything but chrome/webkit. Its a shame but its all i can do to blame it on them.
The memory error is an ipad hardware limitation. There is probably a limit on texture size in the webgl implementatiom they have. For performance reasons you should use images that arent huge anyways.
Instead of using tickount use timer in those expressions, then global timescale will affect them. If you need local timescale youll need to use a variable that increments by the self.dt value each tick.
Prominent
Its simply too much work for me atm. There are more important widely useful features on the wishlist. I could make a simple api quickly but itd be no simpler than doing it in javascript in that case.