Assuming Flash provides fairly clean access to the underlying hardware, performance should be as good as you can expect given the intermediate abstraction layer

Assuming Flash provides fairly clean access to the underlying hardware, performance should be as good as you can expect given the intermediate abstraction layer. On a side note, it would be nice if Unity produced iOS apps that could be extended as easily using Obj-C / CocoaTouch the way it looks like you can work with native AS3 code.