Webpack is a powerful tool for bundling, transforming and optimizing your JavaScript, CSS and HTML for front-end web applications, but it can be hard to get started, and even harder to understand what’s happening inside that build. A simple boilerplate might take a minute to build, and create a many-megabyte JavaScript bundle, before you even add any code of your own—but it doesn’t have to be this way. In this talk we’ll discuss what Webpack is doing when it creates your bundle, and how to inspect the generated code to understand the origin of build performance issues. Armed with that information we will then learn some simple ways to create smaller bundles that rebuild faster, to speed up your own development and to improve the experience for the users of your application!