Simulator performance does not correlate to device performance in a meaningful way. If you want to test performance of an app as it behaves on your users' devices, you must test on a real device. When I say simulator performance in the rest of this document, I mean the performance of the simulator itself, not the performance of the app running in the simulator.
open -a Simulator --args -CurrentDeviceUDID 5FCE6A79-78EF-497A-8329-99D9755C8559