What Is CSS Containment and How Can I Use It? – CSS Wizardry CSS containment lets you isolate layout and paint work to self-contained ‘islands’. Here’s what each contain value does and how to use it safely.

#Development #Guides
How to use CSS containment · An underused technique to improve UI interactivity ilo.im/16brsp by Harry Roberts

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#CSS #Rendering #Browsers #Interactivity #DesignSystems #WebDesign #WebPerf #WebDev #Frontend #DOM

The Great CSS Expansion CSS now does what Floating UI, GSAP ScrollTrigger, Framer Motion, and react-select used to require JavaScript for. Here is exactly how much that saves, why these libraries were painful beyond their size,...

#Development #Overviews
The great CSS expansion · How modern CSS reduces the need for JavaScript ilo.im/16bpqd by Pavel Laptev

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#ModernCSS #Libraries #MotionJS #GSAP #React #WebPerf #WebDev #Frontend #CSS #JavaScript

WebPerformance Report performance email preview highlighting optimization scores, Perf Links, and Core Web Vitals metrics on a colorful gradient background.

⚡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

Three WebPerformance Report email examples showing web performance, accessibility, and security reports on a colorful gradient background.

🎉 WebPerformance Report Week #13 is out! ✅
Join our growing community and subscribe today:
⚡ Web Performance Report: webperformancereport.com
🛡️ HTTP Security Report: webperformancereport.com/httpo/
♿ A11ty Report: webperformancereport.com/wave/
#webperf #websecurity #accessibility #a11ty #ai

WebPerformance Report is no longer just a weekly report in your inbox

Well done, @webperfreport.bsky.social team

#WebPerf #Accessibility #Performance #Security #WebPerfReport

WebPerf Snippets sticker

Did you know webperf-snippets has these snippets to analyze loading performance?

Here are some you might not know about: 🧵

#WebPerf #Performance #WebPertSnippets

The complete audit workflow# With Claude Code or Gemini, Chrome DevTools MCP, and the WebPerf SKILLs installed, the complete audit workflow goes from a series of scattered manual actions to a process the agent runs end to end: 1. Navigate to the URL (navigate_page) 2. Measure Core Web Vitals → run LCP.js, CLS.js, INP.js 3. If LCP > threshold → run LCP-Sub-Parts.js 4. If TTFB > threshold → run TTFB-Sub-Parts.js 5. Analyze resources → run Render-Blocking.js, Preload-Async-Conflicts.js 6. Collect all JSON results 7. Generate report with diagnosis, prioritization, and concrete solutions 8. Export in the required format (markdown, PDF, Slack)

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

WebPerformance Report Board displayed on desktop and mobile, showing a Reporting-as-a-Service platform where users can manage reports, review deliveries, and monitor Performance, Accessibility, and Security trends.

⚡WebPerformance Report is more than a report in your inbox.

Users also get access to their Board to manage reports, review deliveries, and follow Performance, Accessibility, and Security trends over time.

Get your report here: 👉https://webperformancereport.com/

#webperf

The implementation of Container Timing: aggregating paints in Blink Deep dive on the implementation details of the Container Timing API for Chromium. How we track the paints? How we buffer the data for each component?

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...

Congrats @benschwarz.bsky.social and the Calibre team! 🎉👏

RUM landed today and it’s exactly what you’d expect from Ben: focused, privacy-first, and no unnecessary complexity. We used to run into each other a lot at JSConf EU and CSSConf EU in Berlin, good times.

#webperformance #webperf #ux

Would be interested to hear the #webperf community’s perspectives on this. Cc @tunetheweb.com @webperfreport.bsky.social @webperfwg.org @bram.us

Screenshot of a tutorial page titled “Slow Interactions” in a React performance guide. A sidebar on the left lists sections like “Getting Started,” “Unnecessary Re-renders,” and “Slow Interactions.” The main content explains that filtering a large list on every keystroke causes sluggish input because React processes input and list updates with the same priority. A highlighted note emphasizes that the input should respond immediately. Below, a “Hints” section suggests using useTransition and useDeferredValue to improve responsiveness.

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 Cómo combinar scripts determinísticos y agentes de IA para ir de la recopilación de métricas a un informe accionable, y sentar las bases del test de regresión continuo en rendimiento.

IA en auditorías de Web Performance: medición determinística e informes accionables

perf.reviews/blog/ai-web-...

#WebPerf #Performance #PerfReviews #PerfAudit #AI

Container Timing: measuring web components performance An introduction to Container Timing, a new web performance API that lets developers measure when complex components finish painting and shows how to use its native implementation now available behind...

#Development #Introductions
Container Timing · A new API to measure web component performance ilo.im/16bf65 by José Dapena Paz

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#Metrics #Measurement #WebComponents #APIs #Polyfill #Chromium #Browsers #WebPerf #WebDev #Frontend

⚡Featured posts this week from Perf Links by WebPerformance Report:

⚡Featured posts this week:
✨ Telescope Test Agent: Mike Kozicki @nywebperf.com
✨ Agentic SEO for e-commerce: Emilie Wilhelm
✨ The Hidden Costs Behind Modern Frontend: Juntao Qiu
✨ Web Performance Archetypes: @ethangardner.com rdner
🙏 Special thanks to the authors!
#webperf

🎉 WebPerformance Report Week #12 is out! ✅

🎉 WebPerformance Report Week #12 is out! ✅
Join our growing community and subscribe today:
⚡ Web Performance Report: webperformancereport.com
🛡️ HTTP Security Report: webperformancereport.com/httpo/
♿ A11ty Report: webperformancereport.com/wave/
#webperf #websecurity #accessibility #a11ty #ai

How to Compress Image to 100KB (Without Losing Quality) How to Compress Image to 100KB (Without Losing Quality) The fastest way to compress image...

How to Compress Image to 100KB (Without Losing Quality) How to Compress Image to 100KB (Without Losing Quality) The fastest way to compress image to 100KB is to drop it into Pixotter's compress...

#webdev #webperf #tutorial #beginners

Origin | Interest | Match

Check your field CLS: iron-out.io/benchmark/
Guide: iron-out.io/core-web-vitals/cls

#WebPerf #CLS

WebP vs AVIF: Which Next-Gen Image Format Wins in 2026? WebP vs AVIF: Which Next-Gen Image Format Wins in 2026? WebP and AVIF are both "next-gen"...

WebP vs AVIF: Which Next-Gen Image Format Wins in 2026? WebP vs AVIF: Which Next-Gen Image Format Wins in 2026? WebP and AVIF are both "next-gen" image formats that outperform JPEG and PNG....

#webdev #webperf #images #tutorial

Origin | Interest | Match

The 49MB Web Page A look at modern news websites. How programmatic ad-tech, huge payloads and hostile architecture destroyed the reading experience.

#Design #Analyses
The 49MB web page · “Your frustration is the product.” ilo.im/16bcfg by Shubham Bose

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#Business #Publishing #ProductDesign #UxDesign #UiDesign #WebDesign #WebPerf #Development #WebDev #Frontend

SVGs on the web: performance comparison based on how you load them | Joan León Inline, sprite with <use>, <object>, <img>... each way of loading an SVG has different implications for performance, caching and rendering. A practical analysis to help you choose well.

#Development #Comparisons
SVGs on the web · When to use which loading technique ilo.im/16b9sv by Joan León

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#Loading #SVG #Images #Browsers #WebPerf #WebDev #Frontend #HTML #CSS

👉 Le prompt IA : "Recherche des meilleures tactiques pour le référencement " 👉 Le prompt IA :  "Recherche des meilleures tactiques pour le référencement "       🎁 Prompts gratuits : https://vivreaveclia.blogspot.co...

Comment hacker les "Rich Snippets" Google sur mobile ?
L'optimisation AMP n'est pas un hasard, c'est une science.
Ce prompt utilise le "Chain of Thought" pour cela.
Devenez un pro du SEO Mobile.
vivreaveclia.blogspot.com/2026/03/le-p...

#SEO #IntelligenceArtificielle #WebPerf #GoogleAMP

⚡Featured posts this week from Perf Links by WebPerformance Report:

⚡Featured posts this week:
✨ How adidas accelerated passkey adoption: Christopher Kokott
✨ Introduction to the HTTP Archive: @paulcalvano.bsky.social
✨ Speed is the first competency test: @jono.id
✨ Beyond Static Resources: Carlos Mateo
🙏 Special thanks to the authors!
#webperf

🎉 WebPerformance Report Week #11 is out! ✅

🎉 WebPerformance Report Week #11 is out! ✅
🔍 Ready for next Week? Don’t miss out!
⚡ Web Performance Report:👉 webperformancereport.com
🛡️ HTTP Security Report:👉 webperformancereport.com/httpo/
♿️ A11ty Report:👉 webperformancereport.com/wave/
#webperf #websecurity #accessibility #a11ty #ai

Screenshot of the PerfReviews Insights dashboard analyzing joanleon.dev with the “LCP” (Largest Contentful Paint) metric selected. The LCP value is 0.88 seconds, marked Good. The interface identifies the LCP element as a text paragraph with selector .astro-j7pv25f6 and size 40,592 px². The sidebar shows other performance checks including TTFB, images, videos, page weight, and external scripts.

Screenshot of the PerfReviews Insights dashboard analyzing the website joanleon.dev on a mobile viewport (390×844, iPhone 14). The “TTFB” (Time to First Byte) metric is selected in the sidebar. The result shows a TTFB of 203 ms, labeled Good. A connection breakdown chart shows DNS lookup (15 ms, 4%), TCP connect (161 ms, 45%), TLS handshake (158 ms, 44%), and server request (25 ms, 7%). The page includes explanations of the TTFB metric and links to optimization resources.

🚀 PerfReviews Insights: two new metrics to audit your web performance

We've added two new analyses to the tool:

#WebPerf #Performance #PerfReviews #WebPerfInsights

SpeedCurve | How fast is fast enough? Rethinking web performance in pragmagical terms Always remember: We're in the business of creating experiences for other humans.

#Design #Explorations
How fast is fast enough? · Rethinking web performance in pragmagical terms ilo.im/16amva by Tammy Everts

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#Business #Metrics #Conversion #Engagement #Productivity #WebPerf #Design #ProductDesign #UxDesign #UiDesign #WebDesign

“When a website is slow, the problem usually isn’t the website. It’s the organisation behind it.” — Jono Alderson

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#Business #Design #ProductDesign #UxDesign #WebDesign #WebPerf #SEO #Development #WebDev #Frontend #Backend #Quotes

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

feat: experimental Chrome DevTools CLI by OrKoN · Pull Request #1100 · ChromeDevTools/chrome-devtools-mcp This PR enables an alternative CLI interface for Chrome DevTools MCP. chrome-devtools can be used in shell scripts to automate the Chrome DevTools MCP session running as a daemon process. Currently...

The Chrome DevTools MCP 0.20.0 has a new feature: experimental chrome-devtools CLI 🤩

github.com/ChromeDevToo...

#WebPerf #DevTools #CLI #MCP #AI

Episode 10 | PerformanceObserver - YouTube In this episode, Paul Calvano dives deep into querying the HTTP Archive dataset to uncover web trends, while Tammy Everts breaks down the "Performance Platea...

Videos from our last meetup are now live! Check out the talks by @tammyeverts.com and @paulcalvano.bsky.social !

#webperf

www.youtube.com/playlist?lis...