Designing for Performance

Chapter 5. Responsive Web Design

Mobile is no longer “the future.” As mentioned in Chapter 1, handsets are the primary Internet access method (http://slidesha.re/eW8wQ9) for a vast number of global Internet users. People are primarily using handsets to access the Internet, and these devices present their own unique set of challenges. Between the tremendous amount of latency on mobile networks (see “Mobile Networks”) and hardware challenges like WiFi signal strength and battery power (see “Mobile Hardware”), it’s more important than ever that we design and develop sites that are as high performing and efficient as possible. We need to aim for no unnecessary overhead for our users and optimize for perceived performance on all screen sizes.

The challenge with responsive web design sites is that it can be very easy to accidentally deliver unnecessary content like too-large images or unused CSS and JavaScript. Because the process of creating a responsively designed site can often include adding markup and functionality to optimize your layout and content for smaller screens, it’s no surprise that many sites deliver the same page weight or additional page weight to mobile devices without the designers and developers even realizing it.

Many creators of responsive sites are already going above and beyond in their decision-making process: reflowing content, choosing to hide or show various elements, making smart decisions about hierarachy, and more. We need to build an additional step into ...