How to Make Things Faster

Chapter 77. Human Multitasking

A computer uses preemptive multitasking to create the illusion that the machine is devoting all of its attention to you. The principle works beautifully, as long as the scheduler doesn’t take too long to do things like figure out which process in the run queue should run next, pack up the program that’s on the CPU, and load the program being scheduled.

And that’s why preemptive multitasking works fine for computers but not for people: a computer context switch takes a few microseconds, but human context switches take about 25 minutes. They’re expensive in more ways than just wasted time:¹

...Research has also found that multitasking contributes to the release of stress hormones and adrenaline, which can cause long-term health problems if not controlled, and contributes to the loss of short-term memory.

In other words, trying too hard to do more than one thing at once literally makes you sick, and it makes you stupid. If you want high performance from yourself, don’t multitask. Leave that to the machines.

¹ Christine Rosen, “The Myth of Multitasking.” The New Atlantis, Spring 2008, https://oreil.ly/EX1SP.