Given the large amount of mobile users hitting most web applications these days, it is important to be mindful of performance when building new applications. No device will be as fast as developing against localhost, and no phone can match our workstations’ CPUs. To build successful applications, we must take into account the limitations of our users’ devices. This talk will go over a few key concepts to keep your applications feeling snappy for all of your potential users. We will go over basics in measuring performance, code splitting, and service workers. We will then illustrate how to apply our newfound knowledge to building fast, maintainable applications with React.