Why are native setTimeout and clearTimeout calls so expensive? Like, here it takes 1.5 ms. What’s the technical reason it’s so slow? Just 100-200 of those in a row (trivial if you’re mounting a bunch of React components that set timers) will easily block the page.

📢 New blog post! Using the Web Monetization API for fun 🤩 and profit 🤑: 🔗 blog.tomayac.com/2025/11/07/u... Learn how I use the proposed #WebMonetization standard by the @interledger.bsky.social Foundation on my blog to (hopefully) pay for my virtual private server!

Your browser’s already loading the next page… before you click it. Faster loads by predicting what you’ll do next. @tunetheweb.com shares the magic behind Chrome’s new Speculation Rules API. YT: buff.ly/Z5ma0cl Apple: buff.ly/ezPrW1Q Spotify: buff.ly/woBqWvk www.youtube.com/shorts/RXSK0...

Chrome Canary now supports network throttling for individual request URLs! Learn how to try out this new feature: www.debugbear.com/blog/chrome-...

75 years ago today, European nations signed this Convention, so the Holocaust could not be repeated. Beware those who want this to end.

✨ One line of CSS. Smooth page transitions. No JavaScript. ``` @view-transition { navigation: auto; } ``` The 🆕 CSS View Transitions bring native animations to multi-page apps, no SPA setup needed! Explore now 👇 developer.mozilla.org/en-US/blog/...

A little aftermovie to whet your appetite. www.youtube.com/watch?v=ByOC...

Still so amazed by the amazing talks at @perfnow.nl last week 😁 Big thanks to all amazing insights and knowledge shared! @csswizardry.com @tunetheweb.com @michael-hladky.bsky.social I wrote down my learnings and key takeaways, hope they’ll benefit you too! www.tbeeren.com/talks/perfor...

If you're using a cloud provider to host images / videos / other content, you can and should verify the host in Search Console, so that you're aware of potential issues that affect Google's crawling & indexing, & Safe Browsing. Use a DNS CNAME to the bucket, then verify with DNS. More: (1/n)

Good Morning. 👋 I'm just sitting down to write this week's Web Weekly newsletter. If core web development (you know: HTML, CSS and JS) are your thing you should check it out! 👇 webweekly.email This time it'll include Chrome Dev Tools updates, `scroll-padding` and CSS anchor positioning.

Glad to announce that my team at @cloudflare.social released a 1.0.0 version of a cross-browser web performance testing agent that supports Chrome, Firefox, Safari and Edge. Thank you to @tkadlec.bsky.social for making it happen and writing most of the code so far! github.com/cloudflare/t...

You can't make this up.

Disgusted with my family. Disgusted. I was away with work for a week. ALL the clocks are still wrong!!! Over a week after the clocks went back!!!!!!! How can these animals live like this!?!??

Some birdy (thanks @tunetheweb.com) told me that Chrome supports split views behind a flag. 😲 Good stuff! chrome://flags#side-by-side

'She acknowledged that some would question the move given the company was performing well. At the end of July, Amazon reported second quarter results which beat Wall Street expectations on several counts, including a 13% year over year increase in sales to $167.7bn' www.bbc.com/news/article...

performance.now() 2026 will take place on 19th and 20th of November 2026. #perfnow.

Oh nice! Starting with Chrome 142, you can put the bottom drawer to the right side and assign the main panels to it. For example, it's then possible to look at the Elements and Network panel at the same time. I think I'll use this a lot! 👏

No lies detected.

@perfnow.nl for whoever asked that question about Sec-Purpose it DOES get set on sub-resources for prerendered speculations. Not just the document. #perfnow

something very cool to see: Chrome recently shipped automatic <link rel="prefetch"> for all links in viewport you could do it previously with libs like Quicklink, but it’s super cool to see this implemented natively (it’s off by default, enabled with one html tag)

For those who just watched @tunetheweb.com 's presentation, this is the SPDY STREAM he just posted about w/ @yoav.ws + @krzksz.bsky.social of Shopify. Thank again Barry! #perfNow 🎥 youtu.be/DHgoULxvuJ8

Interesting! Etsy implemented speculation rules and got these results: 👍 Time to First Byte on the listing page improved 23.6% 👍 First Contentful Paint improved 20.7% 👍 Largest Contentful Paint improved 21.1% 👍 DOMContentLoaded improved 20.4% #PerfNow #webperf www.etsy.com/codeascraft/...

There's a sight to see, freshly published in time for #PerfNow. Talk by @tunetheweb.com , an excellent walkthrough on how to get the most out of a truly powerful tool www.etsy.com/codeascraft/...

Super talk from @tunetheweb.com on Speculation Rules. Been nervous about using them for fear of false positives on things like Google Analytics. The upcoming prerender_until_script logic sounds like exactly what I need - you'll benefit from fetching subresources, but won't execute scripts. #PerfNow

Neat lil learning from today’s @perfnow.nl (via Umar Hansa): You can now throttle individual requests in Chrome! Neat for experimenting with stuff like - lazy-loading: does the UI look okay if this chunk takes MUCH longer to arrive - resilience: what happens if this specific CDN is extremely slow

#PerfNow request throttling is behind a flag in Canary right now, you can enable it in chrome://flags. But please be aware it's not fully feature complete yet and still being worked on! However it is coming to Chrome stable in the future 🙂

I co-wrote a post on the Etsy engineering blog about implementing Speculation Rules API (SRA) to prefetch product listing pages from search results. And many thanks to @tunetheweb.com and @cdaveross.bsky.social for the help and support! www.etsy.com/codeascraft/...

"I DON'T NEED YOU TO FUCKING REWRITE WHAT I'VE JUST WRITTEN!"

#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...

this is going to be so useful when it finally lands in node 24 and we can make the same router run front/backend cleanly. combined with view transitions? c'mon! web.dev/blog/baselin... (ht @ash.pink for sharing)

Reminder that if you are calling into North American time zone-anchored meetings from Europe, the meetings are an hour early this week. (Unusually only for one week this time.)

🇮🇪 C(ORK) 🛫 ☁️ 🛬 AMS 🇳🇱 Off to The Netherlands for a little weekend break with the family before @perfnow.nl next week! Will I see you there?

Please, please don't use `font-display: swap` with icon fonts. I mean, as a rule, don't use icon fonts — SVGs are so much better — but if you must, then don't use `swap`. It doesn't make sense to see random fallback letters for icons. Do me a favour and check your site now if using icon fonts.

📝 Importing vs fetching JSON JSON imports are now supported cross-browser, but when would you use them rather than fetch()? jakearchibald.com/2025/importi...

Imagine a browser where you type in “Taylor Swift” and it doesn’t even admit that her website exists. I write about Atlas, ChatGPT’s new anti-web browser that should come with a warning label. www.anildash.com/2025/10/22/a...

There’s a new type of CSS scroll-state query coming: “scrolled”. This one remembers the last direction you scrolled into, which you can use to build “hidey bars”: when scrolling down (or having scrolled down), the hidey bar hides itself. When then scrolling back up, the hidey bar reveals itself.

Tomorrow we lose access to the current version of WebPageTest and will be forced into the new version. I’m dreading the switch. Experiments are a HUGE step backwards and I use them all the time. The interface may be consistent with Catchpoint UI, but it is boring and confusing if all you use is WPT.

Welcome to Web Dev Acronyms, a new series decoding the alphabet soup of web performance 🎬 First up is LCP. We're explaining where to find it and how to get help debugging it.

This one has me VERY excited! While I’d love everyone to prerender as that’s where the most gain is, it’s a big lift for many to reduce any risks for that. So how about fetching all subresources AND prerending until you hit your first JavaScript? Massive potential gains with low risk. Love it!

More than *anything* the people who actually know how technology works, who actually build things, wish that people would treat LLMs like every other technology, and be normal about them. Don't build a religion about them, don't force them on people, don't ignore the problems. Just be normal.

Largest Contentful Paint (from Core Web Vitals) is now available in Safari Technology Preview. webkit.org/blog/17504/r...

With View Transitions now being Baseline Newly available, and the View Transition API consisting of various features, it can be confusing to know what is supported in which browser versions. To help with that, I created this VT Feature Explorer (powered by View Transitions) web.dev/blog/same-do...

Great deep dive from @jakearchibald.com ! Personally, I agree that I'm not sure we _need_ progressive rendering even if it works (and this post shows it often doesn't!). Sure it seems obvious it would be better but if that comes at a cost, then not sure I'd rather just get the full image quickly.

Who do you want to hear from, or what topics would you like to hear about on Igalia chats?

For Your Convenience, This CSS Will Self-Destruct scottjehl.com/posts/this-c...

A lot of effort went into this, so hope you like it!

I spy with my little eye both INP and LCP enabled by default in the latest Safari Tech Preview. What with Firefox landing INP in stable yesterday (on top of LCP that they already supported) this means we'll soon have cross-browser support for these two Core Web Vitals! #interop2025 #CoreWebVitals

Firefox 144 now supports INP! 🦊 We just shipped interactionId, the piece that makes Interaction to Next Paint work. It helps browsers connect events from the same interaction and measure how responsive pages really feel. More here: blog.mozilla.org/performance/...

Nerdy stuff! @mozilla.org #Firefox just enabled support for #INP with v144 🎉 I dived into our raw RUMvision data. And yep, can confirm that it works when using Google's web-vitals #JavaScript library 😍 (updated) article + chart + baseline badges in a blogpost: www.rumvision.com/blog/firefox...

Everyone agrees that we're currently in a dotcom era-like AI bubble. People disagree what sort of bubble it is. There are 3 stories one can tell about the dotcom crash: a startup story, a telecom story, and an accounting fraud story. My take: it's giving Enron open.substack.com/pub/davekarp...