Joan León
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nucliweb.net
Joan León
@nucliweb.net
1.7K followers 470 following 470 posts
⚡️ Web Performance Artisan at @perf.reviews | Google Dev Expert in Web Tech | Cloudinary Ambassador | ❤️ Image Optimization | Girona
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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
Reposted by Joan León
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 Joan León
henrihelvetica.bsky.social
This is quite the speed test from @cloudflare.social + I get a CSV of the details. Like getting a fortune cookie after dinner. Raw data but still cool to have.
speed.cloudflare.com
A dashboard of broadband speed test. It shows it download speed of over one gigabyte per second and upload speed of just over 612 MB per second
November 24, 2025 at 10:18 PM
Reposted by Joan León
webperfreport.bsky.social
⚡Featured posts this week:
✨ WebPerf Report on SPDY STREAM: @henrihelvetica.bsky.social
✨ WordPress 6.9 Perf Landings: @weston.ruter.net
✨ I Built the Same App 10 Times: @cheddybop.bsky.social
✨ Start building with Gemini 3: @officiallogank.bsky.social
🙏 Special thanks to the authors!
#webperf
⚡Featured posts this week from Perf Links by WebPerformance Report:
November 23, 2025 at 12:04 PM
nucliweb.net
Aprendiendo qué es Firebase Studio de la mano del gran @carlosazaustre.bsky.social en DevFest Barcelona 2025

#DevFestBCN2025
November 22, 2025 at 1:04 PM
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
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
nucliweb.net
I've updated the WebPerf Snippet "Find non Lazy Loaded Images outside of the viewport" to list images without loading="lazy". Now it shows:

- Total number of images
- Total file size
- Individual details: URL, resolution & file size

#WebPerf #WebPerfSnippets #PerfTools
Chrome DevTools Console showing lazy loading audit results: 46 images without lazy loading detected, totaling 4.34 MB, with a list displaying the first 5 images showing their resolution (900x600) and individual file sizes ranging from 14.63 KB to 104.76 KB.
November 20, 2025 at 6:30 PM
nucliweb.net
Obs.js: context-aware web performance for everyone

csswizardry.com/Obs.js/demo/ by @csswizardry.com

#WebPerf #PerfTools #Performance #WebPerfSnippets
Obs.js – context-aware web performance for everyone
Obs.js reads device and network signals and allows you to build adaptive user experiences.
csswizardry.com
November 20, 2025 at 11:30 AM
nucliweb.net
Dark mode = On
Stack of holographic stickers with 'WebPerf Snippets' text in gradient colors ranging from blue to turquoise to yellow-green against a black background, arranged on a white wooden surface
November 20, 2025 at 10:38 AM
nucliweb.net
Send me some coffee 🫠

#WebPerf #WebPerfEngLive
A browser developer tools screenshot showing a network request waterfall. A selected GET request to a webpage displays its details. On the right side, the response panel highlights two values: “Transmitted Size 1.72 MB” and “Full Size 18.2 MB,” indicating compressed vs. uncompressed file size. The request has status 200, content encoded with Brotli (br), and took about 1.96 seconds to load.
November 19, 2025 at 5:02 PM
Reposted by Joan León
zachleat.com
TIL about the HTML Size Analyzer from DebugBear. Great for finding sneaky Data URIs or large payloads of JSON in your pages:

www.debugbear.com/html-size-an...
HTML Size Analyzer
Break HTML document size down by tag and attribute. Discover bloat like code duplication, large hydration state, and inline images.
www.debugbear.com
November 17, 2025 at 8:18 PM
Reposted by Joan León
henrihelvetica.bsky.social
✨ SPDY STREAM 017 ✨ featuring @verlok.bsky.social of Speed Kit joins us to discuss the Interaction to Next Paint (INP) metric and how you can avoid the most common errors that degrade UI responsiveness. JOIN US!
📆 Wednesday Nov 19th
⏰ 11am EST* (special time), 5pm CET
🔗 youtube.com/live/fTGm2gW...
November 17, 2025 at 3:46 PM
Reposted by Joan León
performanceobserver.dev
Reminder: our next meetup is this Wednesday! Join live for access to Q&A and general chat!

#webperf
performanceobserver.dev PerformanceObserver @performanceobserver.dev · 15d
Episode 8 is next week on Nov 19! Come join us live for access to Q&A and general chat!

We have @aarontgrogg.bsky.social talking about reducing JS workload and @mattzeunert.com walking through synthetic testing with DebugBear! #webperf

All details and add-to-calendar 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
November 17, 2025 at 4:12 PM
nucliweb.net
I reached peak performance using @chromedevtools.bsky.social's Performance panel! #DevBadges

developers.google.com/profile/badg...
Speedster  |  Google Developer Program  |  Google for Developers
Earn this badge by clicking on an insight after running a performance trace in Chrome DevTools' Performance panel
developers.google.com
November 17, 2025 at 7:05 PM
nucliweb.net
Call for Speakers for @codemotion.bsky.social Madrid 2026 is open and I've just submitted 3 sessions!
(2 talks and 1 workshop)

sessionize.com/codemotion-m...

#CodeMotion
Codemotion Madrid 2026: Call for Speakers
The Codemotion Conference is a must-attend gathering for savvy devs and IT professionals craving for insights on the latest technologies, inspirationa...
sessionize.com
November 17, 2025 at 11:04 AM
Reposted by Joan León
mattzeunert.com
HTML parsing speed depends a lot on how powerful the device that's visiting the website is.

When I measure parse time on my laptop it takes under 7 milliseconds to process one megabyte of HTML. But on a low-end Android phone it takes 88 milliseconds!

www.debugbear.com/blog/html-pa...
November 17, 2025 at 10:10 AM
nucliweb.net
Do you know the Web Performance Working Group?

The mission of the Web Performance Working Group is to provide methods to measure aspects of application performance of user agent features and APIs.

www.w3.org/webperf/

#WebPerf #Performance
Web Performance Working Group
A group page
www.w3.org
November 16, 2025 at 5:35 PM
nucliweb.net
AI assistance for performance

developer.chrome.com/docs/devtool... by @matthiasrohmer.bsky.social

#WebPerf #Performance #PerfTools #AI #PerfAI
AI assistance for performance  |  Chrome DevTools  |  Chrome for Developers
Understand performance profiles - with the help of AI
developer.chrome.com
November 16, 2025 at 5:27 PM
Reposted by Joan León
guaca.bsky.social
On today’s lightning-fast trip, I’m rolling with my brand-new backpack.

Look closely and you’ll spot that the design is based on eleventy.config.js from 11ty/eleventy-base-blog by @11ty.dev

I know, I know! I basically own the coolest backpack on the planet 💅
Backpack resting on a train seat, featuring a dark fabric printed with JavaScript code from the eleventy.config.js file.
November 15, 2025 at 12:41 PM
nucliweb.net
El Protocol que va canviar el Debugging: Chrome DevTools MCP i Agents d'IA per a Web Performance

📽️ slides.com/joanleon/el-...
November 16, 2025 at 11:33 AM
nucliweb.net
He propuesto una charla para @t3chfest.es 2026, animate y propón una t3chfest.es/2026/call-fo...
Call for Talks - T3chFest 2026
Propón una charla para T3chFest 2026. 12 y 13 de marzo de 2026.
t3chfest.es
November 16, 2025 at 11:30 AM
nucliweb.net
Quina il•lució em fa participar al #DevFest Girona 2025 ☺️

#GironaDevFest2025
Una mà sosté una acreditació de ponent d’un esdeveniment DevFest davant d’un ordinador portàtil obert. A la pantalla del portàtil es mostra una diapositiva de presentació sobre Chrome DevTools MCP i agents d’intel·ligència artificial per al rendiment web, amb la imatge d’un xip electrònic marcat amb les lletres ‘AI’.
November 15, 2025 at 12:16 PM
nucliweb.net
🤩 How wonderful!

Split View is coming to @developer.chrome.com 🥰, and you can already try it out in the Canary version

#Chrome #Browser
November 13, 2025 at 8:39 AM
Reposted by Joan León
gdggirona.bsky.social
Aquesta és l'agenda del DevFest Girona 2025

#DevFest #DevFestGirona #DevFest25
Cartell del DevFest Girona 2025 amb la data 15 de novembre de 2025. El cartell mostra la primera part de l’agenda de la jornada: • 09:00 – 09:30: Arribada, benvinguda i presentació d’inici. • 09:30 – 10:00: Sponsor spotlight. L’Estació Espai Jove i Bee2Be Tech presenten els seus projectes. • 10:00 – 10:45: De la Idea a la Validació en 48 Hores — Com validar el teu Producte amb 0€. Sergi Laurent, Co-Founder i CEO d’Ocean­dex Labs. • 10:45 – 11:30: ¿Tu Web es Lenta? El Kit de Primeros Auxilios del Developer. Estela Franco, Technical Architect Web Performance a Shopify. • 11:30 – 12:00: Pausa per esmorzar. Amb cafè d’especialitat de Tornado Coffee Roasters i dolços de PdePa. • 12:15 – 13:00: AI-assisted development: El código ya no se escribe, se orquesta. Víctor Martín, CTO. A la part superior apareix el logotip del DevFest Girona i la data dins d’un requadre groc. Cartell del DevFest Girona 2025 amb la data 15 de novembre de 2025. El cartell mostra la segona part de l’agenda de la jornada: • 12:45 – 13:30: Agilitat web: Microfrontends & Native Federation. Jordi Serra, Arquitecte Frontend. • 13:30 – 14:15: La fi del món anunciat: Complexitat i computació quàntica amb dragon ball. Alex Alemany, Student Data Scientist a Saxo Bank. • 14:15 – 15:00: Pausa per dinar i networking, amb menjar de Freshli. • 15:00 – 15:45: Aprende a dominar Gemini. Laura Morillo, Platform Engineer a Seedtag / Cloud GDE. • 15:45 – 16:30: El Protocol que va canviar el Debugging: Chrome DevTools MCP i Agents d’IA per a Web Performance. Joan Leon, Web Performance Artisan. • 16:30 – 17:00: Cloenda. Tancament, agraïments, cafès i dolços a la sortida. A la part inferior hi ha els logotips dels col·laboradors: L’Estació Espai Jove, Bee2Be Tech i Surper.
November 12, 2025 at 4:35 PM