The Cost of Context Switching

Many of us find ourselves split across a number of different projects or assignments. On paper or in planning, this may be seen as maximizing the use of a person’s time and as a way to distribute expertise, costs, etc., across different initiatives.

While this type of split allocation may be a necessary thing, I think it is important to also understand the sometimes hidden costs and impacts associated with context switching.

For each project or initiative we are working on, we can generally expect to lose 20% of our time to context switching. There are a number of studies on this, including the work of computer scientist Gerald Weinberg in his book "Quality Software Management: Systems Thinking," where Gerald talks about this impact in detail.

With one project, 100% of a person’s time is theoretically available for that project. When a second is added, 20% is sacrificed to context switching, leaving only 80%, which is split two ways for each project (40% each). With three projects, only 20% is available to each, and so on. Up to five projects, and a person is spending, at most, 5% on each.

In the past, I have used a bar graph to illustrate this, which does provide a great visualization. However, I always felt that the person element was missing from this view.

I recently came up with another way of illustrating this, which I think is more impactful. Shout out to Trinh Johnson for coming up with the idea of making the time lost to context switching look like TV static. I love this idea of just how fuzzy context switching can feel.

What do you think? What are some ways that you have illustrated this impact or activities you have done to help teach your teams about it?

I would love to know your thoughts in the comments below!