We enabled automatic addition of loading="lazy" for shopify.dev/docs/api/liq... 🚀 On pages using videos, we're seeing 75% reduction in downloaded files and 1.23MB/78% less data transferred! For now only in Chrome, but support in other browsers is coming.

Shipped a follow-up to this that proactively preconnects p.typekit.net when we see Typekit's CSS. Saves another 31ms at p75 for the affected page views bsky.app/profile/krzk...

We now emit preconnects to up to 3 external origins if your Shopify online storefront needs render-blocking resources from them. Thanks to Early Hints, I'm seeing ~30ms improvement in platform-wide FCP. Some stores render up to 264ms faster.

We switched Speculation Rules on Shopify storefronts from conservative to moderate eagerness. Here's how that went: performance.shopify.com/blogs/blog/f...

Faster storefront navigations with moderate speculation rules

We upgraded Speculation Rules to moderate eagerness on all Liquid storefronts. Desktop navigations are now 285ms faster at the median, with near-zero TTFB.

performance.shopify.com

One of the most important pieces about web performance that I've ever worked on is finally live. After a few months of work, my analysis of the correlation between site speed and conversion across the entire @Shopify platform is out: www.shopify.com/enterprise/b...

Store Speed and Conversion: What the Data Shows (2026) - Shopify

How does site speed relate to sales? Find out in this Shopify data deep dive.

shopify.com

Over a week ago we made an improvement that combines two separate domain and path redirects that @Shopify merchants have configured into one 🚀 E.g. www.example.com/watches -> example.com/collections/watches is now a single redirect. A great change for both performance and SEO.

This week we made a change that enables "stale-while-revalidate" caching strategy for "accelerated-checkout-backwards-compat.css". We're seeing 1.7% FCP improvement for same-site navigations across all stores that use the quick buy buttons 🚀

Two weeks ago we shipped changes that cut Portable Wallets execution time by at least 40% at both p75 and p90. INP for interactions related to those scripts dropped ~25%. Overall INP improved by −8 ms (p75) and −16 ms (p90) across all Shopify stores using quick buy buttons 🚀

#JavaScript: When it comes to breaking up long tasks, the scheduler API seems quite convenient: await scheduler.yield(); Alas, not supported by Safari yet: caniuse.com/mdn-api_sche... Thankfully, providing your own fallback implementation is easy: web.dev/articles/opt...

✨ SPDY STREAM 011 ✨ w/ @krzksz.bsky.social & @yoav.ws After deploying the SPECULATION RULES API to their merchants, they join me this week to discuss the experience and their findings. Join us! (updated day and time) 📆 Thursday Sept 25 ⏰ 11am EST, 5pm CEST 🔗 bit.ly/spdy-stream-011