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

chrome-devtools-mcp: v0.14.0 🎉 Features 🔹 add a skill for using chrome-devtools-mcp 🔹 include stack trace in 'get_console_message' tool 🔹 support device viewport and user agent emulation 🔹 support filePath for network request and response bodies 🔹 and more… #WebPerf #Chrome #DevTools

✍️ Just finished another code drawing in my AI series, this one's about MCP in practice. Enjoy!

My talk at @henrihelvetica.bsky.social's SPDY meetup in Toronto is live: www.youtube.com/watch?v=xq2c.... It's pretty rough and unpolished, but I included some fun stories of the history of performance work in Chrome which you likely can't find anywhere else. Slides: docs.google.com/presentation...

In Firefox 147, you no longer need heavy libraries to (de)compress brotli with JS - you can just use CompressionStream and DecompressionStream!

🦀 I'm a member of Rust Girona ☺️ #Rust

The 2025 Web Almanac by HTTP Archive has been officially released! 🚀 We would like to thank all of our contributors from around the globe who made this extensive report possible! Check out the full report here: almanac.httparchive.org

December 2025 dataset is now available & it covers 17,288,655 origins, a decrease of 6.5% over last month 67.6% of origins (↓ 0.5%) had good LCP 80.3% of origins (↑ 0.1%) had good CLS 85.6% of origins (↓ 0.6%) had good INP 54.4% of origins (↓ 0.4%) had good LCP, CLS and INP #CoreWebVitals #WebPerf

Been loving NVIDIA's NeMo models recently to complement Whisper for transcription, but the startup felt a bit heavy. So I went on a profiling adventure! github.com/NVIDIA-NeMo/... Turned out to be fruitful… stoked to land a big optimization in NeMO. github.com/NVIDIA-NeMo/...

I’ve decided to invest time in learning WebAssembly with the aim of improving the performance of some products I know that WebAssembly isn’t a silver bullet that solves everything, but there are use cases where it can significantly improve a product’s UX #WebPerf #WebAssembly #Performance

Did you know you can add annotations to your web performance charts on DebugBear? www.debugbear.com/docs/annotat...

Debugging web performance with Chrome DevTools. @nucliweb.net shows how to triage big assets in Network, read CrUX live Core Web Vitals, and use Performance Insights and traces to improve LCP, CLS, and INP. #performance #devtools #chrome calendar.perfplanet.com/2025/chrome-...

When web performance degrades, the impact is immediate. Conversions drop. UX suffers. SEO follows. The problem? These issues are often detected too late.

A Visual Guide to Fundamentals by @sarahedo.bsky.social www.youtube.com/watch?v=tGnv...

Wrote a bit more about the memory leak we fixed recently, and why we ignored it for 6 years. Thanks to @nucliweb.net for sharing some of his questions! www.debugbear.com/blog/javascr...

New blog post: www.phpied.com/maximally-mi... It's about staying away from most everything the JS ecosystem has to offer and stick close to the web platform. A build is still necessary because of long lived caches and updates but it can be tiny and simple. Time will tell how this strategy plays out

New year, new web performance mystery (and it's a huge one): calendar.perfplanet.com/2025/the-cur...

📣 Nuevo post: Chrome DevTools para depurar el rendimiento de una web Una guía paso a paso de cómo utilizo Chrome DevTools para detectar problemas de Web Performance en una web, así como validar algunas hipótesis joanleon.dev/posts/chrome... #WebPerf #DevTools

🚀 WebPerf Snippets – Major Update ✨ What’s new • Visual ratings 🟢/🟡/🔴 • Clean tables report • Automatic summaries • Issue detection with actionable recommendations • Improved docs with causes, fixes & official links 👉 webperf-snippets.nucliweb.net #WebPerf #CoreWebVitals #JavaScript #DevTools

I’m starting the year by migrating the webperf-snippets.nucliweb.net project to the latest versions. I’m also improving the documentation and scripts, with better console output. Keep an eye out for upcoming updates #WebPerf #WebPerfSnippets #PerfTools #Performance #DevTools

Marketing: Hello, Joan! Can we add a short video as a background in the hero component? Me: 🫠 #WebPerf #Performance #TrueStories

Our Web Performance Journey guide is live on PerfPlanet Calendar!

Web Performance Calendar day 28 when Ian Duffy shows us how to tame Chrome’s Performance panel: reduce noise, search fast, annotate, use Insights, and customize tracks calendar.perfplanet.com/2025/tips-fo...

Web Performance Calendar day 27 with @nucliweb.net on using Chrome DevTools for fun and profit: inspect heavy files in Network panel, monitor Core Web Vitals, record performance traces, validate optimizations, and more. calendar.perfplanet.com/2025/chrome-...

La propiedad CSS content-visibility puede mejorar significativamente el rendimiento de renderizado, especialmente en páginas con mucho contenido En este post: cómo funciona, un caso real con métricas antes/después, y snippets para auditar joanleon.dev/posts/conten... #WebPerf #Performance #CSS

How to load CSS (fast) calendar.perfplanet.com/2025/how-to-... by @yoavweiss #WebPerf #CSSPerf #Performance #CSS

Web Performance Calendar day 21 with Conor McCarthy and lessons learned from web perf client site reviews calendar.perfplanet.com/2025/insight...

Why Your Server Is Paying for Your CSS Choices dp-lewis.medium.com/why-your-ser... #CSS #WebPerf #ServerPerf

Check out all the revised demos of Grid Lanes in Safari Technology Preview 234! webkit.org/demos/grid3/

Updated de Content-Visibility snippet for Chrome DevTools - Detects existing content-visibility usage - Finds offscreen optimization opportunities - CLS warnings for missing contain-intrinsic-size - Configurable thresholds webperf-snippets.nucliweb.net/Loading/Cont... #WebPerf #PerfTools

About to start a new Web Performance consulting project & I’m really looking forward to it I’m sure I’ll enjoy working on this, and the impact on the client’s conversions should be very noticeable 📈 Performance is where UX and business truly meet #WebPerf #WebPerformance #CoreWebVitals #UX

Web Performance Calendar day 19 with Alex Podelko on how performance engineering has evolved with computing: from mainframes to distributed systems, web/mobile, cloud, AI. Knowing your history may help reduce wheel-reinvention and encourage skills reuse calendar.perfplanet.com/2025/a-short...

Lazy loading out-of-viewport images can make the main content on your website load faster. ⬇️ Learn how in this video. www.youtube.com/watch?v=CPJf...

Major update to the CSS Media Queries Analysis Snippet with a Performance Impact Analyzer It calculates the REAL cost of desktop-only CSS on mobile: 📉 Core Web Vitals Impact 💰 Estimated Conversion Lift e.g.: Fixing 30KB of unused CSS 180ms faster load and up to 1.8% conversion boost

I really love the page transition on PerfPlanet’s Calendar 🤩 Smooth details like this make a big difference in web performance and UX. #WebPerf #PerfPlanet #UX

⚡Featured posts this week: ✨ Timeline of web features and browser support: @rviscomi.dev ✨ Fast by Default: @denodell.bsky.social ✨ Analyzing CSS Media Queries to Optimize Perf: @nucliweb.net ✨ What was new in web perf in 2025: @mattzeunert.com 🙏 Special thanks to the authors! #webperf

🤩We just opened the Public Preview of our Reporting as a Service (RaaS) platform before the general release. Users from different countries are already accessing their personal Boards. Explore the platform by getting your own report: 👉 webperformancereport.com #webperf

Half a year ago, I published a pretty long paper about JPEG XL: arxiv.org/abs/2506.05987 I am happy to see that section 11.1 is already outdated!

Chrome DevTools' ~4 GB prompt is your Local LLM onboarding It's the required download for Zero-Exfiltration AI (client-side inference) Benefits: Maximum Privacy (data stays on device) + Low-Latency Debugging Download the weights to use the future of DevTools #DevTools #LLM #OnDeviceAI #Debugging

chrome-devtools-mcp v0.11.0 🎉 Features - emulation: add geolocation emulation tool - integrate DevTools issues into the console tools - support --user-data-dir github.com/ChromeDevToo... #DevTools #mcp #ai #Chrome