Why transatlantic ping is faster than pixel output

“I can send an IP packet to Europe faster than display a pixel on the screen. What the fuck is that? ” Asked John Carmack on his twitter. As his tweet caused a wide resonance in the community, Carmack explained that Sony HMZ-T1 used a program to measure the delay on the full-screen display, which changes the buffer contents by pressing a key on the controller, and a 240 fps video camera. Then counted the number of frames between pressing a button and changing pixels.

The controller works with a frequency of 250 Hz, then you can not measure the delay.

For the sample, Carmack took an old CRT monitor with a vertical sweep of 170 Hz - and on it, under optimal conditions, two frames pass between pressing the button and changing the pixel, that is, a delay of only 8 milliseconds.

But with modern LCD displays, the situation is much worse. The same Sony HMZ-T1 updates the image after 18 frames, that is, 70+ milliseconds. Due to the specifics of the technology, all LCD displays show a worse result than CRT. Is that the latest OLED displays can be compared with the worst of the CRT. According to Carmack's tests, the best result among non-CRT monitors was shown by the Emagin z800, which roughly corresponds to the CRT monitor with a 60 Hz screen refresh rate.
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The problems with the "stagnation" of the Sony HMZ display are explained, among other things, by poor-quality drivers, which, instead of optimizing for performance, try to put everything in the buffer, because it's easier.

Transatlantic ping can be measured with the ping command, which shows the time a packet travels to a remote server and back. It needs to be divided into two.

John Carmack expresses the hope that display manufacturers will draw conclusions, correct mistakes and release faster displays.

On this topic:
Expanding Input Lag Inside and Out , AnandTech