High Performance Android Apps

Chapter 4. Screen and UI Performance

The user interface of your app is likely influenced by designers, developers, usability studies, and testing—just about anyone is happy to add input/feedback to how your app looks. As the UI of your app is your connection to your customers, it defines your brand and it requires careful planning. However simple (or complicated) the UI of your app is, it’s important that your UI design is built to be performant.

As a developer, your task is to work with the UI/UX team and build an app that follows its design parameters on every Android device. We’ve already (briefly) discussed the pitfalls of the many screen sizes in the Android ecosystem and the challenges that exist there. But how about UI performance? How does the UI that your designers designed (and you built) run? Do the pages load quickly? Do they respond in a fast and smooth way? In this chapter, we’ll discuss how to optimize your UI for fast rendering and scrolling/animations, and the tools you can use to profile your screen and UI performance.

UI Performance Benchmarks

Like all performance goals, it is important to understand the performance goals associated with UI. Saying “my app needs to load faster” is great, but what are the expectations of the end user, and are there concrete numbers you can apply to those expectations? In general, we can fall back on studies of the psychology of human interactions. These studies have shown that users perceive delays of 0 – 100 ms as instantaneous ...