Complete aside about Carmack and reducing VR latency from https://www.gamasutra.com/view/news/226112/How_John_Carmack_... :

"He gave the example of increasing the refresh rate on the Gear VR during development. He was working, at that time, with its Galaxy S III phone. Android triple-buffers graphics, inducing a 48 millisecond delay into the system -- making VR impossible.

Carmack pulled apart Android to hack that out. Though he'd written several emails to Samsung in attempts to convince them to give back that buffer, "It's easy to argue against an email, but it's much harder to make the argument when you can have the two things and stick them on your face and, 'Tell me this isn't better.'"