Raiders of the Fast Start: Frontend Performance Archeology There are a lot of books, articles, and online tutorials out there with fantastic advice on how to make your websites performant. It all seems easy in theory, but applying best practices to real-world code is anything but straightforward. Diagnosing and fixing frontend performance issues on a large legacy codebase is like being an archaeologist excavating the remains of a lost civilization. You don’t know what you will find until you start digging! Pick up your trowels and come along with Etsy’s Frontend Systems team as we become archaeologists digging into frontend performance on our large, legacy mobile codebase. I’ll share real-life lessons you can use to guide your own excavations into legacy code: What tools and metrics we used to diagnose issues and track progress. How we went beyond server-driven best practices to focus on the client. Which fixes successfully increased conversion, and which didn’t. Our work, like all good archaeology, went beyond artifacts and unearthed new insights into our culture. We at Etsy pride ourselves on our culture of performance, but, like all cultures, it needs to adapt and reinvent itself to account for changes to the landscape. Based on what we’ve learned, we are making the case for a new, organization-wide, frontend-focused performance culture that will solve the problems we face today.