In this chapter, we have better understood the principles behind UI design when it comes to the perception of performance. We have seen how these design principles can have a real effect on the user's subjective perception of time and how they can improve perceived performance when there are no real optimizations left to do.

We hope that you have found this book useful to better understand the notions of performance and efficiency, to discover most of the new underlying web technologies that make up what the Internet has become today and to help you on your way to mastering the Faster Web.