Testing PerfReviews Insights #WebPerf #Performance #PerfReviews #CoreWebVitals

Software is evolving fast. My focus hasn’t changed: helping teams improve performance, UX, and conversion AI generates working code faster than ever… but not optimized for performance That’s where we add value: from “it works” to “it’s excellent” Reading @addyosmani.bsky.social’s new book

⚡Featured posts this week: ✨ Android Sets New Record for Mobile Web Perf: Eric Seckler ✨ AI in Web Performance Audits: @nucliweb.net ✨ AI Won't Save Your Development Process: @steve8708.bsky.social ✨ Safari 26.4 is here!: @jensimmons.bsky.social 🙏 Special thanks to the authors! #webperf

How do you measure rendering performance for entire DOM subtrees without slowing down the browser? ⏱️ ✍ In my new blog post, I dive into the technical details of how I implemented the new Container Timing #webperf API in #Blink / #Chromium. blogs.igalia.com/dape/2026/03...

WebPerformance Report is no longer just a weekly report in your inbox Well done, @webperfreport.bsky.social team #WebPerf #Accessibility #Performance #Security #WebPerfReport

Did you know webperf-snippets has these snippets to analyze loading performance? Here are some you might not know about: 🧵 #WebPerf #Performance #WebPertSnippets

A measurement that varies with the model's interpretation is not a measurement. It's an estimate. I've written about separating deterministic measurement from AI analysis in web performance audits. #WebPerf #Performance #PerfReview #AI #DevTools

Hello, RUM calibreapp.com/blog/real-user-monitoring

Find the bottleneck. Fix it. Hands on exercises to diagnose and fix the most common performance problems in React apps; from unnecessary re-renders to costly hydration slowreact.vercel.app #WebPerf #Performance #React #ReactPerf

IA en auditorías de Web Performance: medición determinística e informes accionables perf.reviews/blog/ai-web-... #WebPerf #Performance #PerfReviews #PerfAudit #AI

🤯 TIL: "!important" in #CSS can have whitespace after the exclamation point! And not just that, but entire comments as well. It makes sense. You should have to explain why you're using !important, and what better place than the middle of the declaration? Demo 👉 codepen.io/editor/SirPe... #webdev

React SSR Framework Showdown: TanStack Start, React Router, and Next.js Under Load blog.platformatic.dev/react-ssr-fr... by @nodeland.dev #React #Performance

🚀 PerfReviews Insights: two new metrics to audit your web performance We've added two new analyses to the tool: #WebPerf #Performance #PerfReviews #WebPerfInsights

Chrome is bringing AI directly into the browser with the Summarizer API. In this post I show how to add an AI-generated summary to blog posts using the Chrome Summarizer API and models running locally in the browser. No external APIs. No token costs. #AI #WebAI #JavaScript #Chrome

I built a free tool to analyze web performance: no login, no setup. Paste a URL → get an instant report on images, videos, page weight and third-party scripts. It's in beta. Try it 👇 #WebPerf #Performance #PerfInsights

The Chrome DevTools MCP 0.20.0 has a new feature: experimental chrome-devtools CLI 🤩 github.com/ChromeDevToo... #WebPerf #DevTools #CLI #MCP #AI

Muchas webs siguen sirviendo imágenes PNG de 2–3 MB. Pero esas mismas imágenes pueden pesar menos de 50 kB. La optimización de imágenes sigue siendo uno de los mayores problemas de rendimiento en la web. Hilo 👇

When a Skill activates, its SKILL.md loads into context. The webperf-loading was 24 KB, most of it unnecessary to decide which script to run I applied progressive disclosure and brought it down to 11 KB #WebPerf #Performance #AI #AIAgent #AIPerf

Improve Your Website's Performance perf.reviews/en #WebPerf #Performance

⚡Featured posts this week: ✨ WebPerf Snippets and Agent SKILLs: @nucliweb.net ✨ The UX Speed Museum: @sergeyche.dev ✨ The GEO Playbook: @kylerisley.bsky.social ✨ What Are Agent Skills?: @debbie.codes 🙏 Special thanks to the authors! #webperf

WebPerf Snippets agent-first WebPerf Snippets SKILLs were written for humans: emojis, colours, tables. The agent had to parse all of that. I added structured JSON returns and a build with terser that removes the console code. 80 lines → ~300 characters. #WebPerf #AI #Performance

📌 In this brief clip, @sneyers.info underscores the surging industry support for JPEG XL, tracking the momentum that ultimately led to its growing adoption across major browsers. 🎬 ✨ SPDY STREAM 024 ✨, in viewports soon.

The JPEG XL Image Coding System History, Features, Coding Tools, Design Rationale, and Future arxiv.org/pdf/2506.05987 #Image #JpegXL

Open UI has been working on speccing out the focusgroup attribute: a declarative way to support roving focus & add keyboard nav to composite widgets like toolbars/menus We'd love your feedback! Learn more & see open questions: developer.chrome.com/blog/focusgr... H/t to Edge folks for prototyping

I've been using WebPerf Snippets in my audits for years. Scripts to measure LCP, INP, CLS, TTFB, Render Blocking... The next step: turning them into tools an AI agent can use autonomously. But there's a design decision that makes all the difference. 🧵 #WebPerf #WebPerformance #AI #DevTools #MCP

Twang editor.p5js.org/isohedral/fu...

This would be a great addition to every CMS, as a page is published/updated, right before it is cached! 🥰

Taught Claude Code to prioritise loading the first image in a post 😉 #WebPerf

Ever wanted a comprehensive guide to DevTools and debugging front ends? Check out this ebook that Lala Hakobyan just launched: github.com/lala-hakobya... I’m impressed!!

Practical guide to the <img> element: from basics to LCP. @nucliweb.net shows how srcset, sizes, modern formats AVIF and WebP via <picture>, fetchpriority, preload for the LCP image, and CDNs can improve Core Web Vitals. #performance #html joanleon.dev/en/guia-prac...

Interested in the @httparchive.org and not sure where to start? During the @performanceobserver.dev meetup tomorrow (12:30pm ET), I'm going to be providing an overview of the HTTP Archive and demonstrate how to start querying it! performanceobserver.dev/events/episo...

New Blog post by me! Pre-compressing HTML to Brotli 11 using the #11ty build pipeline and serving via Cloudflare pages & a Cloudflare Worker #eleventy #webperf #perfmatters #cloudflare nooshu.com/blog/2026/02...

Last week I delivered a Web Performance training for part of the Basetis technical team: 2 days of theory and hands-on practice with real cases. We covered Core Web Vitals, RUM & Lab monitoring, Chrome DevTools, Lighthouse CI, Playwright and more... at the iconic La Pedrera. #WebPerf #Training

Practical guide to the <img> element: from the basics to LCP joanleon.dev/en/guia-prac... #WebPerf #ImagePerf #Performance #LCP #CoreWebVitals

Guía práctica del elemento <img>: de lo básico a LCP joanleon.dev/posts/guia-p... #WebPerf #ImagePerf #Performance #LCP #CoreWebVitals

I've been updating WebPerf Snippets for Chrome DevTools, and this weekend brought 10 new tools for diagnosing web performance directly from the console. New snippets in webperf-snippets: 🧵 #WebPerf #WebPerformance #ChromeDevTools #CoreWebVitals #JavaScript #WebDev

I've encountered many applications with poor INP due to long tasks that do not yield control to the browser I've written a guide with measurable examples comparing setTimeout, queueMicrotask, scheduler.postTask. It includes snippets to audit your projects joanleon.dev/en/yield-to-... #WebPerf

Performance-Optimized Video Embeds with Zero JavaScript frontendmasters.com/blog/perform... #WebPerf #Performance #Video

I've been experimenting with an upcoming CSS feature called border-shape lately. It's really cool what you can do with it: lots of practical applications + it opens a lot of doors for non-rectangular UIs! Try it in Canary w/experimental web platform features on, & read more: una.im/border-shape

Optimize rendering with content-visibility joanleon.dev/en/content-v... #WebPerf #Performance #CSS

🚀 New WebPerf Snippet published! Detects potential performance issues with `rel="prefetch"` resource hints by analyzing quantity, size, type, and appropriateness of prefetched resources. webperf-snippets.nucliweb.net/Loading/Pref... #WebPerf #WebPerfSnippet #PerfTools

📖 Nuevo artículo, “Optimización de scripts de consentimiento para Core Web Vitals” joanleon.dev/posts/consen... #WebPerf #Performance #CoreWebVitals #JavaScript

How do you measure when a component is “ready”? ⏱️ LCP is too global; Element Timing is too specific. 🛠️ I’ve been working with Bloomberg on a new #webperf API: Container Timing. Think of it as “LCP for a web component”, providing aggregated paint timing for a subtree.

🚀 New WebPerf Snippet published! Detects preload resource hints for scripts that use async or defer attributes. This is an anti-pattern that wastes bandwidth & can hurt performance by artificially elevating the priority of resources that should load at lower priority #WebPerf #WebPerfSnippet

Integrate CrUX data into performance trace summaries in Chrome DevTools MCP v0.17.0 👏 github.com/ChromeDevToo... #WebPerf #PerfTools #DevTools

We recently added support for adding specific URLs to our CrUX trends dashboard – not just entire domains! www.debugbear.com/docs/crux-tr...

A shocking 8.5% of sites that use CDNs deliver some static content directly to end users via cloud storage! Many are not compressing or caching this content either. This comes at a significant performance cost. Details, examples and @httparchive.org stats here - paulcalvano.com/2026-02-09-s...

Announcing The CSS Selection! 📰 www.projectwallace.com/the-css-sele... 📚 100,000 websites ⏱️ 100+ metrics 🔖 7 chapters The biggest deep-dive ever into real-world use of CSS across the globe. Dive in and find out some hidden gems. Also, see how much of 'the new CSS' is actually used!

Excited to share my latest contribution to the Web Performance Calendar 2025! In this post, I dive into using Chrome DevTools for debugging web performance, with tips to help you speed up your sites and improve user experience. #WebPerf #Performance #DevTools #PerfTools

Here's your friendly reminder that CSS selectors are global and evaluated RTL, so if you have selectors that are very broad like `.container > div` you might be impacting performance in a measurable way 🙈 Before and after profile of server switching after some selector optimizations in @discord.com