7 Fresh Links on Performance For March 2022

I have a handful of good links to articles about performance that are burning a hole in my bookmarks folder, and wanna drop them here to share.

• From fonts to SVG: an icon migration strategy— Erwin Hofman notes that he was using icon fonts out of sheer convenience, but that there are loads of reasons not to use them. He provides details on his new strategy for using icons, which is based on the <use> technique. Five years later, I’m still a big fan of just dunking the <svg> in the HTML where you need them. It’s just an HTML partial like any other.
• Next.js Performance: Making a Fast Framework Even Faster— Ben Schwarz says that Next.js is already a pretty fast framework in that it does smart things that keep even React powered pages snappy. But performance isn’t something that can be left entirely to a framework. You have to do work. Fortunately, Next.js has some pretty handy helpers for things like dynamically (lazily) loading components, deferring scripts, optimizing images, and more.
• Redirect Liquidation— Tim Vereecke covers a fascinating technique where instead of redirecting an old URL to a new URL, you let the old URL load, dynamically load the new content, then history.replaceState the old URL with the new URL. It’s faster, but just don’t do it for bots.
• Performant A/B Testing with Cloudflare Workers— Philip Walton covers how A/B testing is a little trickier on static sites than server-backed sites, but you can pull it off (performantly) thanks to Cloudflare Workers which can manipulate HTML before it hits the browser, much like a Service Worker except at the edge rather than at the client. Save a cookie and you can maintain users in their proper groups.
• A Unified Theory of Web Performance— Alex Russell tries to answer Tanner Hodges’ call for actually defining web performance. It’s one of those things that seems obvious (like it’s clear when certain things help and hurt web performance) but actually defining it is tricky. And not just defining it in terms of specific metrics (even that is tricky), but answer questions like: What are this discipline’s guiding principles? What does it look like to practice web performance? How do we do it?
• Unveiling the new WebPageTest UI— I absolutely love seeing WebPageTest’s design evolve and improve. It’s one of those products that’s clearly a best-in-class tool for performance practitioners, yet had a prettttty gnarly design for a lot of years. This is way better. It’s like when Google Fonts finally got a redesign and the broad community let out a collective exhale of appreciation.
• Caching Header Best Practices— Simon Hearne’s dissertation on Cache headers. When I first started caring about web performance, this was, like, the main thing. If you incorrectly send Cache headers, users might be re-downloading a file over and over unnecessarily when they don’t need to, which is about the worst thing possible. I’m glad to see headers keep getting attention and re-imagined as the web evolves.