High Performance Web Sites: Essential Knowledge for Front-End Engineers This book? All kinds of interesting. I’ve been writing about performance a little bit here recently and this well written, concise book has really helped to expand my understanding of some of the issues involved. It also opened my eyes to a few new possibilities for performance improvement here at this site. One of which I’ll be implementing some time this week- passively caching the “next” and “previous” images in all of my gallery flows. Meaning, if you land on this page, JS will work in the background downloading the images featured on the Next and Previous links. And no, that won’t help my YSlow grade, Mr. YSlow junkie (actually there’s not much I can do beyond dropping things like Google Analytics and Google Ads), but it will definitely help my users and that’s the real point, isn’t it?