On my iPhone 3GS I noticed that when tapping on text fields inside forms it takes around 500ms for field to receive focus. Since I have more than one field, tapping on previous and next keys on virtual keyboard would put a focus almost instantly so I think this should be somehow related to tapping.
I have seen this happening in ST 2 kitchen sink demo and apps written in ST 1 that I downloaded from the app store.
Is there something that can be done to improve the form fields focus speed? My users are complaining about slow response of app I'm building.