High Performance Responsive Design

Chapter 2. Primer on Performance of Web Applications

The Basics of Measuring Performance

If you are reading this book, the chances are good that you have an idea of what performance is, or at the very least, you have had some discussion around the performance of your web applications. But before we go any further, let’s make sure we are on the same page with respect to terminology.

If this is your first time hearing the term web performance optimization, quickly go pick up a copy of Steve Souders’s books High Performance Web Sites and Even Faster Web Sites (both from O’Reilly). These are the standards in web performance, and they represent the base level of knowledge that all web developers should have.

The goal of this chapter is not to cover every nuance of performance. There is an enormous corpus of work that already achieves that goal, starting with the aforementioned publications of Steve Souders. Rather, the goal of this chapter is to give an overview of performance, both web performance and web runtime performance, including some of the tools used to measure performance. This way, when we reference these concepts in later chapters, there should be no confusion or ambiguity.

When talking about the performance of websites and web applications, we are speaking either of web performance or runtime performance. We define web performance as a measurement of the time from when an end user requests a piece of content to when that content is available on the user’s device. We define runtime ...