Very few developers have the need to write super optimized code. In application development we tend to favor readability over optimization. But that’s not the case with frameworks. Developers who use frameworks expect them to run as fast as possible. In fact, speed is often a defining characteristic when choosing a framework. There are techniques that make code run faster. You’ve probably heard about linked lists, monomorphism and bitmasks, right? Maybe you’ve even used some. Well, you can find all these and a bunch of other interesting approaches in the sources of most popular JS frameworks. Over the past year I’ve seen a lot while reverse-engineering Angular and React. In this talk I want to share my findings with you. Some of you may end up applying them at work. And others, who knows, may even end up writing the next big framework.