John Carmack posted on Twitter:

I can send an IP packet to Europe faster than I can send a pixel to the screen. How f’d up is that?

Somebody asked about that on superuser, John Carmack went on to explain why it was like that. He didn’t just cross reference a few sources to come to his conclusion: he measured, he checked his assumptions with experiments. He acted like a scientist, adapting his mental model to the world.