Heard of the Supporters of Chromium-Based Browsers (aka SoCBB)? No? Well, we at Microsoft came together with Meta, Opera, and Google to fund improving code, fixing bugs, interop issues in Chromium, so it stays healthy. Said another way: get paid to fix chromium bugs!

Right now, if you import something from JS, and the result is a 404 (or other not-ok status code), it fails the load & gives you nothing. I wonder with json imports, and maybe even text/byte imports, if that's the right pattern github.com/whatwg/html/...

Should modules really be 'null' if the HTTP status code is not-ok? · Issue #12657 · whatwg/html

What is the issue with the HTML Standard? https://html.spec.whatwg.org/multipage/webappapis.html#fetch-a-single-module-script:~:text=response%27s%20status%20is%20not%20an%20ok%20status%2C,-then%20s...

github.com

Soft navigations Intent to Ship!! groups.google.com/a/chromium.o...

The Chrome DevTools team are doing a "papercuts" sprint where they try to address lots of small, irritating bugs and annoyances. Reply with crbug.com links (no bug, no fix—that's the deal!) and will see what we can do. No promises though as some may be features/too big/unclear how to solve.

PSA: Features available behind a feature flag have not shipped. (The thread had some more examples and words)

Bramus@bram.us · 2mo ago

Maybe one thing to clarify here is that this hasn’t shipped. It is _available for testing_ in Chrome _behind a feature flag_ (the Experimental Web Platform Features flag) so that you, developers, can try it out before we actually ship this (unflagged).

I'm proposing a way to be able to persist iframes across navigations github.com/WICG/proposa... Best idea or worst idea??

Persistent iframes · Issue #289 · WICG/proposals

Introduction Hard navigations of top-level documents result in the destruction of all the child iframes of those documents. In cases of same-origin navigations, there's high likelihood that at leas...

github.com

Speed still matters. "for every 100 milliseconds slower a store loads, conversion tends to be about 3.5% lower. (...) For every 32 milliseconds slower a store responds to interactions, conversion tends to drop by about 1.5%." 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

Container Timing is a new browser performance API for measuring when an area of a web app has been displayed. It is available in an Origin Trial in Chrome 148 🎉 Read the blog post below to learn more 👇

Jason Williams@jason-williams.co.uk · 3mo ago

Excited about this, we've been working on the upcoming Container Timing API. Want to learn more? Take a read of the blog post below, put together with @tunetheweb.com and @jdapena.bsky.social. Feedback is very welcome. Try it out and help us shape this API! [This feature is Mozilla Approved]

I say it every year - if you're even the least bit interested or involved in web performance, this is THE place to be every year. It's the one trip I prioritize my travel budget for. The talks are awesome, but the hallway track is unbeatable. The concentration of experts in one place is insane.

performance.now() conference@perfnow.nl · 3mo ago

performance.now() 2026 is coming. Ticket sales will open in May with cheap and ultra-cheap early bird tickets. These will be announced in our newsletter first. So subscribe via perfnow.nl/subscribe perfnow.nl

I'm very excited about this! Have seen some really significant impact in our tests. With the sizes of websites and JS payloads continuing to increase, this is both important and impactful.

Cloudflare@cloudflare.social · 4mo ago

Today, we’re excited to give you a sneak peek of our support for shared compression dictionaries, show you how it improves page load times, and reveal when you’ll be able to try the beta yourself. https://cfl.re/42egXfC

*web frameworks klaxon* If you work on a web framework then there is a w3c proposed community group: the Web Frameworks Community Group, a place for framework folk to feedback to browser vendors about what they want to see! If you want this it needs your support! www.w3.org/community/gr...

After implementing Compression Dictionaries back in December, I sat down with @yoav.ws and @patmeenan.com to discuss getting the most out of them and provide some visuals for those new to the concept. Check out the video below: youtu.be/YR2er3EiYnM / lessonsofacto.com/videos/032-c...

Compression Dictionaries: How Google & Shopify Are Bringing SPA Speed to MPA Websites

YouTube video by Lessons of a CTO

youtu.be

Something I've been helping @yoav.ws with. A proposal to allow you to measure Speculation Rules API and <link rel=preload> usage. Are you over-speculating? Under-speculating? Until now you've only really been able to measure secondary impact, but with this proposal you'll can have better data.

IntentToShip@intenttoship.dev · 6mo ago

Blink: Intent to Prototype: Speculative load measurement

Speeding up CSS with compression dictionaries. @yoav.ws shows how combining critical and full CSS via compression dictionaries cuts bandwidth and accelerates page transitions. Works now in Chromium. #performance #css calendar.perfplanet.com/2025/how-to-...

shout out to @frehner.me for adding name only container queries in Safari! bugs.webkit.org/show_bug.cgi...

Web Performance Calendar day 13 with Yoav Weiss (@yoav.ws) showing us a clever and creative way to ship *only* critical/necessary CSS for each page type (home, search, etc) while also avoiding duplicate code in the CSS bundles. calendar.perfplanet.com/2025/how-to-...

How to load CSS (fast)

Loading styles on the web is something that looks trivial at first. You just add a <link rel=stylesheet> to your page (or <style> for inline styles) and you're done. But if you wanted to load CSS fas...

calendar.perfplanet.com

We have Custom Elements, but do we also need Custom Attributes? This was discussed at TPAC. Is it something you'd like on the platform? https://github.com/WICG/webcomponents/issues/1029

Out-of-order HTML patching, another proposal from TPAC, lets HTML be presented non-linearly, and a single file can update multiple parts of the page. Would this feature be useful to you?

Compression dictionaries is now an official RFC! www.rfc-editor.org/rfc/rfc9842....

I'm proposing a change to iframes that will allow child frames synchronous access to data attributes on the parent frame. Let me know your thoughts: github.com/blittle/ifra...

GitHub - blittle/iframe-data-attributes: Iframe Data Initialization Attributes

Iframe Data Initialization Attributes. Contribute to blittle/iframe-data-attributes development by creating an account on GitHub.

github.com

✨ 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

@lukewarlow.dev I just discovered github.com/whatwg/fetch... thanks to @jakearchibald.com Something like this has been a recurring request at the WebPerfWG, beyond `fetch()` github.com/w3c/resource... It'd be great if this could cover both!

WIP: Add a mechanism to fetch to track progress by lukewarlow · Pull Request #1843 · whatwg/fetch

This is not ready for review this is WIP. At least two implementers are interested (and none opposed): … … Tests are written and can be reviewed and commented upon at: … Implementation b...

github.com

📝 Fetch streams are great, but contrary to popular belief, they're not good for measuring upload/downloading progress. ⬇️ Here's why, and how to avoid the gotchas ⬇️ jakearchibald.com/2025/fetch-s...

Fetch streams are great, but not for measuring upload/downloading progress

They're inaccurate, and there are better ways.

jakearchibald.com

Great post and it's been a pleasure helping @krzksz.bsky.social and @yoav.ws get this working on Shopify. performance.shopify.com/blogs/blog/s...

Speculation Rules at Shopify

We all love quick and snappy online shopping experiences. Fast navigations from one product page to the next reduce friction and allow people to find all the products they want in that store. To achie...

performance.shopify.com

Starting my new role on Monday. Could be anywhere.

today is my 40th birthday. to toot my own horn a bit, I'm the happiest, healthiest, and most successful I've ever been, so I'm going to indulge myself and do one of those "40 things that made me who I am" threads so buckle up (or mute me for the next little bit 😆)

Blink: Intent to Implement and Ship: Http cookie prefix

CSS uses a complex algorithm to decide how to animate transforms. If you get it wrong, as many folks do, you end up with an unnatural animation. Here's how it works, and how to avoid the pitfalls. jakearchibald.com/2025/animati...

Animating zooming using CSS: transform order is important… sometimes

How to get the right transform animation.

jakearchibald.com

In case anyone out there is looking for a good-first Chromium bug, issues.chromium.org/issues/42421... is one I'd be happy to mentor someone through..

What do y'all think of reviving <img lowsrc>? (as a data URI, used until the real image loads)