Been a hot minute, but working through some of the case studies that were submitted to wpostats.com but not yet put live. Starting with a pair of INP-relevant studies from PubTech and ContentSquare. wpostats.com/2025/09/15/p... & wpostats.com/2025/09/15/c...

👀 Safari plans to ship LCP and INP in 2025?! Be still my beating heart. webkit.org/blog/16458/a...

This is incredible data from @dbelson.com showing HTML requests from crawlers versus referrals from that platform. Very easy to see the cost of AI here. ClaudeBot: 70.9k requests : 1 referral (!!!) OpenAI: 1.6K : 1 Perplexity: 202.4 : 1 blog.cloudflare.com/ai-search-cr...

Pumped for this. The line-up is stacked (with more coming soon) & the community around the event has gotten better and better each year with amazing conversations throughout, side events, large standards & browser involvement—it's wild to think about how this has taken off from its 1st year.

Lake Superior remains undefeated

For those of you who watched my talk at @webexpo.bsky.social, the bug I mentioned regarding speculation rules and GET/POST looks like it should be fixed in Chrome v138. chromium-review.googlesource.com/c/chromium/s... h/t @tunetheweb.com

Thanks again to everyone who came to my #WebExpo talk about the intersection of site speed, #UX and business metrics – and how to make a data-driven business case for investing in #webperf. My slides are up. I'd love to hear your questions and feedback! speakerdeck.com/tammyeverts/...

Heading home after a great #webexpo with a nice mix of old friends and new. Doesn't hurt that Prague is beautiful with ample dessert options. :)

I’m speaking at @perfnow.nl this October about Accessibility and Performance! Super looking forward to it. perfnow.nl/speakers.html

In all my years of flying, my luggage has been lost three times and three times only. I have been to Prague three times and three times only. The venn diagram is a full circle.

I'm just a guy, sitting in front of his computer, begging companies to please stop making me talk to AI "support" and let me talk to an actual human being instead.

Been wondering why a bunch of sites have been SUPER slow lately. Turns out it's the @1password.bsky.social chrome extension doing really bad things. :/ Gonna have to disable for awhile.

One thing about deadlifts: if you get sloppy with your form, you'll be _painfully_ aware of it. This message has been brought to you by lower back pain.

Drinking plenty of mulled wine and watching Rudolph, as our forefathers intended.

This is so well deserved. Not only is Pat one of the most brilliant people I've ever had the opportunity to work with, but he's so generous with his time—I wouldn't be able to do what I do without all the times over the years that Pat patiently answered my questions and helped me figure things out.

Suggesting people are advising against relying heavily on the popular JS architecture you work on because they're stuck in 1995 is an incredibly out of touch statement and doesn't exactly instill me with confidence that the actual issues will be resolved anytime soon.

The first performance.now() 2024 video is up: @tammyeverts.com discusses the current web performance landscape as an introduction to day 1. www.youtube.com/watch?v=MR2R...

Spotted in the wild - Dictionary content-encoding for display ads. Pretty sure the feature usage chart for dictionary encoding is about to take a pretty big jump.

This year's web perf calendar is off to an excellent start with Noam reminding everyone about Goodhart's law and the importance of remembering _why_ we're optimizing for perf in the first place calendar.perfplanet.com/2024/goodhar...

I've been threatening to write a post for awhile now about how elegant standards like Speculation Rules are, as they are built in a way that provides an natural progression for rolling out. @csswizardry.com does an _excellent_ job of demonstrating it in his latest: csswizardry.com/2024/12/a-la...

There are pumpkin pie M&M's. I'm not sure if I like them yet or not. I plan to continue eating them until I can provide a clear recommendation for you all.

Forcing Google to sell Chrome is one of those ideas that may sound ok in principle, but the practicalities are scary. Google throws a lot of resources at browser & standards work. If that's split off, do they still? Mozilla is on rocky ground at the moment, and Apple obviously has diff priorities.

performance.now() 2025 will take place on 30th and 31st of October, 2025. #perfnow.

The 5th annual #perfnow was an absolute blast. Obviously a bit biased, but I really do think it's become a must-attend for anyone working on performance or performance related tooling. Great talks, lots of old and new friends, incredible conversations—always come back with a mountain full of ideas!

This is the A/B test from @tkadlec.bsky.social that @anniesullie.bsky.social referred to during her #perfnow talk. timkadlec.com/remembers/20...

"Always iterate". @anniesullie.bsky.social Good advice for product management, performance experimentation and so much more. I'm a huge proponent of the "what's the least amount of work we can do to see if we're on the right path" approach. #perfnow

Deployed a quick China web compatibility testing tool together just for the @perfnow.bsky.social community, v 1.0. Let me know what you think⚡️ #perfnow #performancegaps

So far: holy moly do those talks at #perfNow do a good job at interlinking (is that a word?) each other! Nice work indeed!

Proud to announce the new W3C RUM community group, live from @perfnow.bsky.social, Nic Jansma, @cliffcrocker.bsky.social and I will co-chair and for everyone who uses RUM, join us! www.w3.org/community/ru...

At #perfnow, @ericwbailey.website made great points about how improving the INP metric, which measures latency after user interactions, can improve accessibility as well: reducing the amount of JS that runs after user interactions can reduce delays in updating assistive technology after interactions

Steps to build a web app in 2024 by @ericwbailey.website at @perfnow.bsky.social #perfNow #webPerf

I really like @csswizardry.com's framework on different metric types: KPIs, enablers and predictors. Splitting metrics to ones you target vs. ones that help you in process of figuring out regressions or plan for improvements #perfnow

Starting the annual pilgrimage to Amsterdam for perfnow.nl

Friendly reminder that when a third-party provider requires you to load their script in a render-blocking manner, their problems become your problems. Always build with resilience in mind.

Me, a professional, who gets paid to help companies with performance, looking at a popular indoor hydroponics garden company's site, knowing darn well I could just buy the thing: I wonder if they would give me a free stand if I helped them fix their performance?

Today in "our tools need to get better"..... Next.js driven HTML doc is 2.6MB, 1.5MB of which is all of Next's generated inline JSON stuff.

🚀 perfwork is now live! https://www.perfwork.com I wrote a little bit about why I built it, and a little bit about what I've got in mind going forward. https://timkadlec.com/remembers/2023-07-26-introducing-perfwork/

Started working with these folks in mid-May and not gonna lie, pretty pleased with the progress they've made on INP in such a short span of time. From a p75 of 4.25s in April (90% of sessions having a poor experience) to a p75 of 225ms in June (9% of sessions have a poor experience).

In a thread talking about why perf doesn't matter and it's a waste of time to focus on it: "users on 3G don't buy anything" 🤔 I wonder why that is?

We interrupt my usual performance posts for, I guess, a potential 🌶️ spicy take: design by democracy is less likely to ruin your product than the single visionary fairytale. https://timkadlec.com/remembers/2023-06-30-single-visionary-fairytale/

Fetching a record from Supabase: ~250ms Fetching the same record from DynamoDB (with help from https://github.com/beginner-corp/begin-data): ~6ms I think Dynamo wins this round.

Is there like....an AWS billing for dummies thing? Trying to calculate some potential costs and I'll be honest it's been awhile since ap calculus so it's taking me a bit (seriously this feels like it could be a lot less obnoxious)

Phew. What a difference a `:last` makes in jQuery. Third-party Shopify app with a very long list of selectors in a click handler. With the deprecated `:last` selector: ~616ms Without: ~16ms (Talked to the app devs and they're looking at it now so hopefully this gets fixed)

Improving performance isn't about ticking some boxes on a checklist: it's about ensuring the folks using our sites have a better experience & can efficiently accomplish their goals. To do that, we have to make sure the way we measure performance lines up accordingly.

A solid, timely reminder from @adactio.com that improving performance has broad implications and can directly impact (among other things):- Business Metrics - Sustainability - Inclusivity https://adactio.com/journal/20154

I love talking about Bluesky but what I look forward to most is when we start talking about tech again in the fun way- not griftery things but the genuine discussions about tech that some nerds like me still find exciting

While they sound similar, First Contentful Paint & Largest Contentful Paint don't use the same underlying API, so "contentful" means something different for each. Wrote a bit diving into the differences with some "fun" examples. https://timkadlec.com/remembers/2023-04-23-growing-contentful-gap/

Been using https://enhance.dev/ quite a bit the past week or two—early take is nothing but positive! It's almost _hard_ to build something isn't lightweight & fast. The entire dev approach strongly encourages progressive enhancement. And there's so little overhead—it really is just JS, HTML & CSS.