Rendering performance on the modern web is messy. We have fancy browsers on slow devices (think: phones) that let you create all sorts of snazzy effects, and most of it is really slow. The web was never designed to do real-time animation, but we’re trying to teach this old dog yet another round of new tricks so it can compete with the fluid, animation-heavy experiences the mobile touch device revolution (think: iPhones) has trained users to expect. Let’s blow the covers off of what’s going on when the browser renders your web page. Rather than do this by explaining all the complicated technology involved, your humble hosts from the Chrome rendering team will just take a few website and show you what it looks like when we do performance profiling. We’ll bounce from CSS all the way down to the GPU and back using the tools we’ve built to analyze Chrome performance.