Latency

Latency is the delay between action and reaction. Having low latency is crucial when using a Head-mounted Display for VR or AR. As you move your head, your HMD should display the resulting changes immediately. Any significant delay will cause your brain to reject the legitimacy of the virtual world and cause you to lose presence. High latency can also cause Motion Sickness.

End-to-end Latency??

Motion-to-photon latency??