You've probably heard about the radical gains in JavaScript performance in the latest crop of Internet browsers. In this talk, we'll discuss the key insights and optimizations implemented in browser JavaScript engines, such as Chakra in Internet Explorer 10 or V8 in Chrome. More importantly, we'll explore best practices for taking advantage of these optimizations in your code and learn how to pinpoint JavaScript performance problems using appropriate tools. Throughout the presentation, we'll cover tips, tricks, and tools for developing fast applications with JavaScript.