This is a very broad question. You must be more specific with your performance requirements (versus what performance you currently see). Firstly, you might try setting your app's Vsync to every Vblank. This might improve the framerate because NatCam's preview framerate is capped to Unity's. Secondly, increase the framerate of the DeviceCamera that you are running from. It would be very helpful if you have profiled NatCam and can reference specific behaviors in its performance that you are looking to address.