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PerfReviews
@perf.reviews
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🇺🇸 Experts in web performance, we help you to solve performance issues

🇪🇸 Expertos en web performance, te ayudamos a solucionar problemas de rendimiento

https://perf.reviews/
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perf.reviews
PerfReviews @perf.reviews · Nov 5
We Improve Your Website's Performance

Increase your revenue and make your users happier with our web auditing and optimization services

👉 perf.reviews/en

#WebPerf #Performance #PerfReviews
We Improve Your Website's Performance Increase your revenue and make your users happier with our web auditing and optimization services.
Reposted by PerfReviews
webperfreport.bsky.social
⚡Featured posts this week:
✨Why Your Server Is Paying for Your CSS: David Lewis
✨Nuxt Scripts for improved Perf and Sec: @jacobandrewsky.bsky.social
✨Chasing BFCache navigations: Nicolas Hodin
✨TTFB doesn’t mean what you think: @programmingart.bsky.social
🙏Special thanks to the authors!
#webperf
⚡Featured posts this week from Perf Links by WebPerformance Report:
December 28, 2025 at 12:10 PM
Reposted by PerfReviews
infrequently.org
Lots of great stuff in this year's Perf Planet Advent/December series:

calendar.perfplanet.com/2025/
December 28, 2025 at 3:39 AM
Reposted by PerfReviews
stoyan.me
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-...
Chrome DevTools for Debugging Web Performance
This is a step-by-step guide on how I use Chrome DevTools (DevTools from now on) to detect Web Performance issues on a website, as well as validate hypotheses to fix some of the problems found. Discl...
calendar.perfplanet.com
December 27, 2025 at 2:47 PM
Reposted by PerfReviews
nucliweb.net
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
Optimiza el renderizado con content-visibility | Joan León
La propiedad CSS content-visibility mejora el rendimiento de renderizado. Caso práctico con métricas y snippets para detectar oportunidades.
joanleon.dev
December 27, 2025 at 11:25 AM
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nywebperf.com
Happy Holidays!

Join us on January 15 — "Frameworks for humans in the age of machines" with Rich Harris - @rich-harris.dev

RSVP now: www.meetup.com/web-performa...

Rich is the creator of svelte.dev and rollupjs.org

This is a joint event with @sveltesociety.dev NYC

#webperf #wpo #perfmatters
Frameworks for humans in the age of machines - Rich Harris, Thu, Jan 15, 2026, 6:00 PM | Meetup
**Svelte** turns **10 this year** — an eon in web development. After so much time, and at a moment when engineers are increasingly outsourcing the work to agents, is there
www.meetup.com
December 22, 2025 at 6:49 PM
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nucliweb.net
How to load CSS (fast)

calendar.perfplanet.com/2025/how-to-... by @yoavweiss

#WebPerf #CSSPerf #Performance #CSS
How to load CSS (fast)
Loading styles on the web is something that looks trivial at first. You just add a <link rel=stylesheet> to your page (or <style> for inline styles) and you're done. But if you wanted to load CSS fas...
calendar.perfplanet.com
December 22, 2025 at 9:01 AM
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nucliweb.net
Why Your Server Is Paying for Your CSS Choices

dp-lewis.medium.com/why-your-ser...

#CSS #WebPerf #ServerPerf
Why Your Server Is Paying for Your CSS Choices
Server-side rendering makes some previously invisible costs very visible. This post explores how styling can end up on the server’s hot…
dp-lewis.medium.com
December 21, 2025 at 9:56 AM
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webperfreport.bsky.social
⚡Featured posts this week:
✨ LCP and INP are now Baseline: @tunetheweb.com @mmocny.com
✨ Faster pages with Compression Dictionaries: @karlijnlowik.bsky.social
✨ A Short History of Perf Engineering: Alex Podelko
✨ Next.js Perf Optimization: Dany Paredes
🙏 Special thanks to the authors!
#webperf
⚡Featured posts this week from Perf Links by WebPerformance Report:
December 21, 2025 at 1:27 PM
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nucliweb.net
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
Content Visibility – Nextra
A curated list of snippets to get Web Performance metrics to use in the browser console or as snippets on Chrome DevTools by Joan León
webperf-snippets.nucliweb.net
December 20, 2025 at 12:41 AM
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stoyan.me
Web Performance Calendar day 18 with Amrik Malhans on breaking down LCP to pinpoint what's slowing down the page exactly and where to focus your UX-optimizing efforts

calendar.perfplanet.com/2025/the-ana...
The Anatomy of LCP - A Deep Dive into Sub-Parts
Optimizing LCP (Largest Contentful Paint) is not just reducing the file size of your images, there's a lot more that goes into optimizing the loading strategy - and you can only grasp where the bottle...
calendar.perfplanet.com
December 18, 2025 at 11:37 PM
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tammyeverts.com
I ❤️ writing these annual wrap-up posts. From broad browser support for key metrics to nuanced metrics for diagnosing issues, 2025 has been filled with huge wins — not just for @speedcurve.com but for our entire #webperf community. Go, us!

www.speedcurve.com/blog/2025-we...
SpeedCurve | 2025 was a big year! Here are some highlights...
From broad browser support for key metrics to nuanced metrics for diagnosing issues, 2025 has been filled with wins.
www.speedcurve.com
December 18, 2025 at 10:29 PM
Reposted by PerfReviews
nucliweb.net
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
Chrome DevTools showing a JavaScript snippet named ‘CSS Media Queries Analysis’ alongside the Console output. The console summarizes media query usage for min-width > 768px, reporting 336 media rules, 1,146 classes, and 2,595 properties. It highlights potential mobile savings of 170.34 KB of CSS, mostly from external files, with sections for inline CSS, external CSS files, and performance impact analysis. Chrome DevTools Console displaying the ‘Potential Savings’ and ‘Memory Impact’ sections of a CSS Media Queries Analysis. The output estimates savings for a median mobile device, including eliminating 534 ms of render-blocking time, reducing INP by ~9 ms per interaction, and saving 170.34 KB of bandwidth. It also shows estimated CSSOM memory overhead (~336 KB) and total unnecessary memory allocation (~506 KB), with notes about impact on low-end devices. Chrome DevTools Console showing a detailed ‘Performance Impact Analysis’ for unnecessary CSS. The panel breaks down render-blocking time, CSS parsing, CSSOM construction, and total blocking time across high-end and mid-range mobile devices. It lists impacts on Core Web Vitals such as FCP, LCP, INP, and TBT, with millisecond-level timing estimates.
December 16, 2025 at 9:07 AM
Reposted by PerfReviews
nucliweb.net
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
December 10, 2025 at 12:10 PM
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webperfreport.bsky.social
🤩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
December 6, 2025 at 1:41 PM
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sneyers.info
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!
December 6, 2025 at 8:07 AM
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stoyan.me
Web Performance Calendar day 5 when @myshov.bsky.social shows us how to move heavy image decoding off the main thread. Drawing images in freezing your UI and causing long tasks? Not anymore!

calendar.perfplanet.com/2025/non-blo...
Non-blocking cross-browser image rendering on the canvas
Canvas-based rendering has become a prominent tool for building complex web UI interfaces. When working with large images on canvas, one critical challenge stands out: keeping the main thread responsi...
calendar.perfplanet.com
December 5, 2025 at 4:06 PM
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ericportis.com
Speculation Rules on touch devices (where there's no hover) is a hard problem but it sounds like Chrome's making some good progress? htmhell.dev/adventcalend...
Speculation rules improvements - HTMHell
A collection of bad practices in HTML, copied from real websites.
htmhell.dev
December 5, 2025 at 6:51 AM
Reposted by PerfReviews
nucliweb.net
- Use a tag for semantic HTML
- Sure, I’ll do it

#SendMeCoffee 🫠
Screenshot of Chrome DevTools showing an HTML <section> element with the class “about-gallery-1,” containing a <span> and an empty <picture> tag. A red box highlights this section in the Elements panel. An arrow points to the Styles panel on the right, where CSS rules for .webp .about-gallery-1 picture and .about-gallery-1 picture are displayed, including a background-image property and layout styles.
December 2, 2025 at 6:11 PM
Reposted by PerfReviews
nucliweb.net
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
Release chrome-devtools-mcp: v0.11.0 · ChromeDevTools/chrome-devtools-mcp
0.11.0 (2025-12-03) 🎉 Features emulation: add geolocation emulation tool (#634) (3991e4c) integrate DevTools issues into the console tools (#636) (d892145) support --user-data-dir (#622) (fcaf553)...
github.com
December 3, 2025 at 10:56 PM
Reposted by PerfReviews
nucliweb.net
📣 New WebPerf Snippet

Analyze all @media rules in CSS to identify classes and properties targeting viewports bigger than a specified breakpoint. Results are grouped by inline CSS and external files, with byte size estimates for potential mobile savings.

#WebPerfSnippets #WebPerf
A browser window showing the Renfe website on the left with a mobile-style layout, including a menu button, the Renfe logo, travel selection fields, and a Black Friday banner. On the right, Chrome DevTools is open to the Console tab, displaying a CSS Media Queries Analysis report. The report lists totals for media queries, classes, and properties, highlights estimated mobile CSS savings of 284.83 KB, and breaks down inline and external CSS statistics.
November 30, 2025 at 7:33 PM
Reposted by PerfReviews
nucliweb.net
Análisis de Media Queries en CSS para Optimizar el Rendimiento

joanleon.dev/posts/analis...

🇬🇧 version in thread

#WebPerf #CSS #WebPerfSnippets #PerfTools #DevTools
Análisis de Media Queries en CSS para Optimizar el Rendimiento | Joan León
Descubre cómo analizar las media queries del CSS para detectar y optimizar estilos no utilizados en mobile, mejorando el rendimiento de tu web con un simple snippet de JavaScript.
joanleon.dev
December 2, 2025 at 5:08 PM
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nucliweb.net
📣 Updated my Resource Hints snippet for @chromedevtools.bsky.social

Now detects common mistakes like:

❌
❌ Non-standard rel values Perfect for auditing preload, prefetch, preconnect, etc

webperf-snippets.nucliweb.net/Loading/Reso...

#WebPerf #PerfTools
Resource hints – Nextra
A curated list of snippets to get Web Performance metrics to use in the browser console or as snippets on Chrome DevTools by Joan León
webperf-snippets.nucliweb.net
November 25, 2025 at 11:38 PM
perf.reviews
With @chromedevtools.bsky.social, we can streamline Web Performance Debugging with the help of the AI assistant

#WebPerf #PerfTools #PerfDebugging
A screenshot of a performance review interface titled “Perf Reviews” with the question “Which LCP phase was most problematic?” An AI assistant response shows analysis results indicating that the “Time to first byte (TTFB)” phase contributed 4,311 ms (92.8%) of the total 4,648 ms Largest Contentful Paint time, while “Element render delay” contributed 337 ms (7.2%). Below the response are action buttons such as “How can I reduce the time to first byte (TTFB)?” and “What caused the LCP element to render slowly?”
November 25, 2025 at 3:41 PM
Reposted by PerfReviews
nucliweb.net
Dr. @guaca.bsky.social explains the diagnosis with @debugbear.com of our symptoms at DevFest Barcelona 2025

#DevFestBCN2025 #WebPerf #PerfTools #DevFest
November 22, 2025 at 10:55 AM
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nucliweb.net
Nuevo post "Más Allá de INP: LCP y el 90% invisible del rendimiento" de la serie de Long Animation frames API (LoAF)

joanleon.dev/posts/loaf/m...

#WebPerf #Performance #LoAF #LCP #CoreWebVitals
Más Allá de INP: LCP y el 90% invisible del rendimiento | Joan León
Descubre cómo LoAF va más allá de INP. Aprende a detectar scripts que bloquean el LCP y a distinguir entre JavaScript pesado y layout thrashing para aplicar la optimización correcta.
joanleon.dev
November 21, 2025 at 7:11 PM