Why is Steve Karnacki's touchscreen so laggy?

Alec Jacobson

December 18, 2024

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For whatever reason, during elections and the NFL playoffs, networks will drag out a big touchscreen and draw on top of it for live graphics. I guess it gives the feeling of watching something unfold immediately like how the telestrator has been used for a long time in live sports broadcasts.

Unlike the telestrator, Steve Karnacki's touchscreen is extremely laggy.

The response is about a third of a second behind 🤯. No wonder the handwriting is so bad. This must be unbearable to use.

I'm sure the resolution is high on the screen, but what's really the cause? My two hunches are: 1) the software they're running got bloated out of control and is no longer keeping up with the machine it's running on, or 2) the filtering on the touch input is extreme (and poorly implemented). The resulting curve looks way over-smoothed. Using over-smoothed inputs for drawing is very frustrating.

The worst part is that the lag has got way way worse over time.

CNN Guy using a touchscreen (Jeff Han's Perceptive Pixel) to draw a circle back on Super Tuesday in the 2008 US election. Notice there's almost way lower latency.