### Writing performant JavaScript applications is a complex matter these days, involving various tools like script concatenation, minification, tree shaking, and module bundlers. ES6 modules have been defined in the ECMAScript specification for a while but were slow to be implemented in browsers. The article discusses how to use ES6 modules with Webpack and other build tools, and how they can improve performance by reducing bundle size and improving code execution. However, it also highlights some challenges, such as dealing with minification of ES6 code, preloading of modules, and the need for a proper build process and "bundle strategy". The article concludes that while ES6 modules offer many benefits, frontend development is still complicated, and measuring performance is key to success.