@nucliweb

⚡️ Web Performance Artisan at @perfreviews_ | @GoogleDevExpert in #WebTech | @cloudinary Ambassador

 Girona, Catalunya
nucliweb.net
Joined August 2008
  • Tweets21.5K
  • Following4.3K
  • Followers12.1K
And thank you to @carlesnunez too for the @framer sticker ☺️
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Thank you to @andrey_sitnik for the @evilmartians sticker ☺️
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The case against JPEG XL Investigating JPEG XL's place as a Web image codec, by Gianni Rosato, via @WebPerfReport giannirosato.com/blog/post/c… #JPEGXL #JXL #ImagePerf #WebPerf
A dark-themed line chart titled “SSIMULACRA2,” showing BD-Rate (%) versus encoding speed in milliseconds for several image codecs. Colored lines compare codecs including AOM, JPEG XL, aperture-alpha, Iris-WebP, libjxl, SVT-AV1, and libwebp, with labeled data points. Most curves show higher BD-Rate at slower speeds, while some reach negative BD-Rate at faster speeds.

ALT A dark-themed line chart titled “SSIMULACRA2,” showing BD-Rate (%) versus encoding speed in milliseconds for several image codecs. Colored lines compare codecs including AOM, JPEG XL, aperture-alpha, Iris-WebP, libjxl, SVT-AV1, and libwebp, with labeled data points. Most curves show higher BD-Rate at slower speeds, while some reach negative BD-Rate at faster speeds.

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P75 is green: LCP 1.58s, INP 176ms, CLS 0.01. P90: LCP 2.68s, INP 352ms, CLS 0.17. 15% of visits get a noticeably worse experience. Product Performance doesn't end once you pass CrUX. If P75 is good, work on P90. #WebPerf #CoreWebVitals #ProductPerformance
DebugBear RUM dashboard showing Core Web Vitals at the P75 percentile: Largest Contentful Paint 1.58s, Interaction to Next Paint 176ms, and Cumulative Layout Shift 0.01, all flagged green on the score bar.

ALT DebugBear RUM dashboard showing Core Web Vitals at the P75 percentile: Largest Contentful Paint 1.58s, Interaction to Next Paint 176ms, and Cumulative Layout Shift 0.01, all flagged green on the score bar.

DebugBear RUM dashboard showing Core Web Vitals at the P90 percentile: Largest Contentful Paint 2.68s, Interaction to Next Paint 352ms, and Cumulative Layout Shift 0.17, all flagged orange or red on the score bar.

ALT DebugBear RUM dashboard showing Core Web Vitals at the P90 percentile: Largest Contentful Paint 2.68s, Interaction to Next Paint 352ms, and Cumulative Layout Shift 0.17, all flagged orange or red on the score bar.

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I love the optimization: web, rendering, images, video, and now tokens. @lydiahallie published a great guide to Maximizing the value of your Claude Code sessions claude.com/blog/maximizing-t… #AIOptimization #AI #Claude
A dark-themed presentation slide titled "TL;DR" displaying tips for optimizing Claude API usage and token efficiency. The slide is divided into two columns: Left column discusses: - Using `/clear` command between tasks to prevent context carryover and reduce token usage - Setting model and effort level before starting a session to avoid breaking the prompt cache mid-conversation - Mentioning files with @ notation instead of naming them, to attach files directly and save API calls Right column covers: - Adding quiet flags to commands or running them in a subagenr to manage noisy output while keeping results in the conversation - Running `/context` once per session to review loaded content (CLAUDE.md and MCP tool definitions) and remove unnecessary items - Running `/compact` before breaks, since prompt cache expires after an hour and summarizing conversations is cheaper while the cache is active

ALT A dark-themed presentation slide titled "TL;DR" displaying tips for optimizing Claude API usage and token efficiency. The slide is divided into two columns: Left column discusses: - Using `/clear` command between tasks to prevent context carryover and reduce token usage - Setting model and effort level before starting a session to avoid breaking the prompt cache mid-conversation - Mentioning files with @ notation instead of naming them, to attach files directly and save API calls Right column covers: - Adding quiet flags to commands or running them in a subagenr to manage noisy output while keeping results in the conversation - Running `/context` once per session to review loaded content (CLAUDE.md and MCP tool definitions) and remove unnecessary items - Running `/compact` before breaks, since prompt cache expires after an hour and summarizing conversations is cheaper while the cache is active

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A letter from @addyosmani landed in my mailbox today, thanking me for my work on Agent Skills. I got in through web performance and stayed for the rest. Thinking about contributing to open source? Start small. Docs and honest reviews count. github.com/addyosmani/agent-…
A printed thank-you letter from Addy Osmani on a dark background, hand-signed and dated 2026, next to its opened envelope postmarked San Francisco. Four stickers lie beside it: "Coder", "Computer Club", a Cmd+Z one reading "Just Undo It", and a perfume bottle reading "#perfmatters".

ALT A printed thank-you letter from Addy Osmani on a dark background, hand-signed and dated 2026, next to its opened envelope postmarked San Francisco. Four stickers lie beside it: "Coder", "Computer Club", a Cmd+Z one reading "Just Undo It", and a perfume bottle reading "#perfmatters".

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The pattern backs it up. Isolated spikes off a stable ~2s baseline, on different days, from different countries. Not one user on a bad connection. And yes, I checked, these aren't bot hits.
SpeedCurve budget dashboard: status "Over", latest value 27.93s against a 0.15s budget, 18,520% over. The weekly chart shows a stable baseline around 2s with sharp isolated spikes above 20s on Jul 29, Jul 31, Aug 3 and Aug 4.

ALT SpeedCurve budget dashboard: status "Over", latest value 27.93s against a 0.15s budget, 18,520% over. The weekly chart shows a stable baseline around 2s with sharp isolated spikes above 20s on Jul 29, Jul 31, Aug 3 and Aug 4.

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The site is static, hosted on Netlify. A CDN-served page taking 27s to first byte means that request never resolved at the edge: cache miss going to origin, cold start, or something failing at a specific PoP.
SpeedCurve size metrics: HTML 15 KB, inline styles 14 KB, inline JS 8 KB. Below, the sessions table lists a session at 7:06 AM from the United States on Chrome 149, with an average First Contentful Paint of 27.93s.

ALT SpeedCurve size metrics: HTML 15 KB, inline styles 14 KB, inline JS 8 KB. Below, the sessions table lists a session at 7:06 AM from the United States on Chrome 149, with an average First Contentful Paint of 27.93s.

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Update: this isn't frontend. TTFB is 27.44s of a 27.93s FCP. 98% of the time is spent waiting for the first byte. The HTML is 15 KB.
SpeedCurve time metrics: Backend (TTFB) 27.44s, Frontend 8.18s, Start Render 27.93s, First Contentful Paint 27.93s, Largest Contentful Paint 27.97s, Page Load 35.62s. First Input Delay and INP both 0 ms.

ALT SpeedCurve time metrics: Backend (TTFB) 27.44s, Frontend 8.18s, Start Render 27.93s, First Contentful Paint 27.93s, Largest Contentful Paint 27.97s, Page Load 35.62s. First Input Delay and INP both 0 ms.

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This SpeedCurve alert fired on its own: the FCP (RUM) budget was breached, metric at 4.72s. Flat and green for hours, then it climbed. Nobody was staring at a dashboard.
SpeedCurve alert: the First Contentful Paint (RUM) budget exceeds its 0.15s threshold by 3047%, reaching 4.72s. The chart shows the metric flat and green until 20:00, then climbing and spiking to nearly 5s.

ALT SpeedCurve alert: the First Contentful Paint (RUM) budget exceeds its 0.15s threshold by 3047%, reaching 4.72s. The chart shows the metric flat and green until 20:00, then climbing and spiking to nearly 5s.

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