Comment by _rknLA

Re: the gotchas, it's possible that this is due to how the app is architected in combination with how the phone and OS are architected. The input rate of 3D Touch, for example, is tightly coupled to the display output frame rate, which, in turn, is tightly coupled to the things you do on the main thread. I don't know off-hand if the camera input is coupled to anything in this way, but it's something to look into, and Apple's documentation should indicate this sort of behavior.