Web performance is a marathon, not a sprint. Ship the fastest site today and in two weeks a third-party script, an unoptimised image or a CDN change will have quietly undone it. Optimising without monitoring doesn't last. 🧵 #WebPerf #RUM #CoreWebVitals
Sergey Chernyshev
@sergeyche.dev
I care about UX speed and organize NY UX Speed and Web Performance meetup
Technology, like time, cannot be stopped in it's relentless march forward. Much as us old timers would like to slow down one or the other just a little bit… In light of that, Chrome 153 will come with an updated list of modern devices for emulation mode—with nice categorisation—thanks to @jackf.io
Laura got Rudy the dog off the streets, do good and good will come to you: youtu.be/2kOY93THkdQ?...
I Need Your Help Saving This Dog!
YouTube video by Laura Kampf
youtu.be
I am feeling that with introduction of AI we might have less obvious changes in SDLC that can be quite useful. For example, the cost of modeling and visualizing system requirements might be so much lower that architectural decisions can be more informed. UX Speed Calculator was one of those tools.
My AI generates them quite frequently. Is there something useful here to save time / better workflow or just a better UI?
Stacked PRs, now on GitHub. Go forth and stack 🥞
I believe we need to make test suites accompany every RFC to get implementations easier to deliver for all of those interested. As Patrick said in his blog, using our newly acquired robotic friends to write those makes it much more achievable now.
Folks, if you’re implementing compression dictionaries, @patmeenan.com just dropped a test suit to help you!
Folks, if you’re implementing compression dictionaries, @patmeenan.com just dropped a test suit to help you!
Finally, a CLI/module for testing compression dictionary deployments: blog.patrickmeenan.com/2026/07/26/t... Thanks to @programmingart.bsky.social @sergeyche.dev and @yoav.ws for not letting me continue to ignore building it 😂
We got a few new individual sponsors recently in @e18e.dev - thank you to those of you who are supporting us 🙏 Getting sponsorships for a community is much harder than for a popular web app or dev tool. Every little helps. If you'd like to help us improve perf for all of us, check out our OC 🩵
e18e - Ecosystem Performance - Open Collective
The e18e community has the aim of improving performance of tooling and packages in the JavaScript ecosystem.
opencollective.com
Amazing resource for anyone trying to understand performance profiles 👏🏻
In my audits, reading the Performance profile is where people get stuck: the flame chart and waterfall look like noise at first I built an interactive guide to make them click, every figure is interactive, plus LCP, CLS, INP and the Insights panel perf.reviews/profile-guide #WebPerf #DevTools
The best SaaS I am paying for is @playingcardsio.bsky.social which allowed me to create Preferans board which I use with two American friends to play the game remotely since pandemic started. I’m looking forward to these games every time and this SaaS enabled it for me.
Yay! Good to see it released in the main branch! Soft Navs are the next best thing after the sliced bread in history ;)
I've just release v6.0.0 of the web-vitals library. It includes support for measuring Web Vitals per soft navigation (like those used in SPAs) for supporting browsers (Chrome 151+) to give more accurate performance metrics for those sites. github.com/GoogleChrome...
+++ Speaker Spotlight: Barry Pollard +++ What if browsers could stream HTML where it's needed, without all the JavaScript? At Fronteers Dark Mode, Barry Pollard explores Declarative Partial Updates, a proposal that could reshape server-rendered apps. Oct. 2nd in Dordrecht 🇳🇱⛵️ 🎟️ fronteersconf.org
Chrome 151 beta introduces powerful capabilities for web performance and accessibility → goo.gle/4yuqBcV Discover new soft navigation timeline entries, the aria-actions attribute, and the <usermedia> element for interacting with media streams.
The curse of web performance - once you know it, you can’t unknown it and I see performance issues on the sites I visit too and can’t help it but open DevTools often as well. I was even thinking for creating a podcast-style Meet4SPEED YouTube channel looking at websites and improving them.
An occupational habit: I open DevTools on every site I visit, hunting for things to improve. On skills.addy.ie I caught a 301 on every internal click, a wasted round trip. It was a trailing-slash mismatch. Wrote up the finding and the fix: joanleon.dev/en/trailing-... #WebPerf #Astro #Netlify
Watched “I swear” yesterday - a very good movie and amazing performance by everyone. It is heartbreaking how mental illness has stigma around it even though people don’t choose to have it. Not everyone’s Tourette’s is as intrusive as media portrays, but it doesn’t make it easier. Be kind, people!
LEGO smart play bricks are cool - I could not resist and got myself Luke’s X-wing.
My talk from last year's @perfnow.nl is now out. Come for the dad jokes & advice on how to troll your kids, stay for my thoughts on stubborn empathy for our users as the foundation for web perf & two threats to the web: the monoculture and the machine. www.youtube.com/watch?v=Dvpi...
Stubborn Empathy - Tim Kadlec - performance.now() 2025
YouTube video by Web Conferences Amsterdam
youtube.com
As I head into the onsite phase with a bunch of cool companies, figured I’d put out one last call… ⚡️Would you like someone to make your frontend-heavy app faster or otherwise build/improve/take care of your frontend architecture or infrastructure? That person could be me! DM me! 🔥
i want to do a little ✨ ama about atproto ✨ in this thread. no question is too simple if you’ve been curious about atproto but don’t know much (anything?) about it, ask any question and i’ll try to explain it in my own words. (+ would love to hear from friends who aren’t very active on bsky)
Videos from our meetup yesterday are up! @sergeyche.dev discussed why the speed of user experience matters and the UX Speed Museum. Almudena explored the environmental cost of Generative AI, sharing practical strategies. #webperf www.youtube.com/playlist?lis...
Episode 12 | PerformanceObserver - YouTube
In this episode, Sergey will discuss why the speed of user experience matters, walking us through the evolution of Core Web Vitals and unveiling the UX Speed...
youtube.com
Video from my talk yesterday at @performanceobserver.dev giving a short intro to UX Speed: youtu.be/-sySoTZVPko
Introduction to UX Speed with Sergey Chernyshev | PerformanceObserver
YouTube video by PerformanceObserver
m.youtube.com
I like this analogy too - let’s figure out how to feed all of our greens.
"we're building rainforests, not skyscrapers" diverse ecosystems with lots of different life forms and symbiotic relationships and growth! @schlage.town got me feeling hopeful, talking about building an Atmospheric (sub) stack
Video from @zeigenvector.bsky.social's "React Performance in the Age of AI" is up! www.youtube.com/watch?v=FvxI... Subscribe for more! #webperformance #nyc
React Performance in the Age of AI
YouTube video by NY Web Performance Meetup
youtube.com
I play GitTerra on my DrawLeather codebase - you can see project progress here: sergeychernyshev.github.io/drawleather/
Your Repo Map | GitTerra
A map of the world automatically built from your code repo using GitTerra
sergeychernyshev.github.io
Does anyone have any good pointer on how to approach converting product manager’s prototypes into a working code? Both are AI-assisted, both have the same scope, both extend the same software. What’s different?
🚨 Next Performance Observer episode will be on July 8 🚨 🎤 @sergeyche.dev will present "Introduction to UX Speed" 🎤 @mrsdaehin.bsky.social will talk about "Don't thank the AI: Sustainability and Performance" 📅 July 8th 🕧 6pm CEST / 5pm BST / 12pm EDT / 9am PDT 🔗 Zoom link at performanceobserver.dev
PerformanceObserver: A virtual web perf meetup
Join the PerformanceObserver virtual performance meetup to get all the latest web performance news and hang out with the community.
performanceobserver.dev
Somebody notice the addictive properties of AI chat systems and I think I am feeling the effect. Not happy about it, but at least I create things with it…
Web developers, designers, and engineers: what Layout and Rendering features do you need from Safari? Bugs count too, I want to hear what you need?