Lesson Outline

Perceived Performance

I struggled with where this lesson should belong - the performance module, or the user interface and user experience module? It is very much a UI/UX matter as it has no impact on the actual performance of the application, but it does greatly affect how performant your application feels to the user.

I think this concept is critical to understand in the context of both of these modules, so I will be briefly be covering some concepts in this module, and we will spend more time in the UI/UX module walking through specific implementations.

What is Perceived Performance?

You know how often weather services will report a "feels like" temperature as well as the actual temperature? Some factors like the wind and humidity can make the temperature feel hotter or colder to humans than it actually is.

A similar concept applies to performance, the way in which our application is designed can alter the user's perception of how performant it is. There may be no actual difference.

A big part of making an application feel faster is to provide feedback to user interactions as quickly as possible. We've run into scenarios in this module where we have clicked a button and faced a delay before the page actually started loading due to a massive amount of rendering we were asking the browser to do. The process for this specific interaction looked something like this:

1. Click page button
2. Wait ~2 seconds as page loads
3. Navigate to page