She was a genius. Was a great character.
If your input processing and font rendering pathways waste microseconds (and they do) it makes a delay in characters you type showing up on the screen, and a corresponding, measurable reduction in your editing throughput.
When our machines were a thousand times slower, characters showed up on the screen in substantially less time than they do today. The difference is mainly a result of cumulative wasted microseconds, in so many places that nobody can afford to gather them up.
The speed of signal propagation is largely determined by the density of the wire's insulation, because the signal is an electromagnetic wave carried at the skin of the conductor, with its electric field oscillating in the insulation, so propagation is limited by properties of that. The distance covered in a nanosecond is typically between seven and eight inches. In wires with foam insulation (typically co-ax) signals go a little faster. In optical fiber, a nanosecond is under seven inches, because the speed is determined by the same property of the glass, which is denser.
(Given the quality of the video, I'd be inclined to think 1983 rather than 1993)