How Web Performance Is Perceived By Users

In this article, Denys Mishunov explores how the brain perceives web performance and introduces us to Psychological Performance Optimisation (PPO)

Before getting to the psychological part of performance optimisation, let’s answer one question, what is web performance? For the majority of frontend developers the answer would include something exciting like: 100-millisecond response time, animations with 60 frames per second, loading a page within one second and many other numbers. Guess what? The world is a cruel place and unfortunately not only web developers have access to the web. It’s a public place that is also used by regular users who seem to be forgotten in our definition of performance. But what do they think about web performance? Usually it’s fast or slow. “SpeedIndex of this site isn’t as good as of that one. 280 milliseconds slower first paint is the reason, I guess,” – said no user without DevTools ever. These diverging views on performance come from the fact that time can be observed from two points: objective and subjective or psychological.

Objective is the time we can measure with a stopwatch and is what we, developers, mean by performance: seconds, milliseconds, etc. On the other hand psychological time is the time as it’s perceived by users. The reason why we should be looking at psychological performance is that unless users perceive the site as fast or faster, whatever we’ve done to our performance optimisation matters very little. We fail the main purpose of our optimisations.

TIME PERCEPTION IN HUMANS 

Perception of time by humans is a complex process. We can sense the flow of time, but the exact nature of the mechanism by which this is done remains unclear. The lack of a dedicated brain area for temporal processing makes understanding the process difficult. This does not mean we are out of control. There is enough knowledge about it for the purpose of performance optimisation. Let’s start with the basic functional mechanism.

EVENT IN A NUTSHELL