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mattzeunert.com

@mattzeunert.com
493 followers 168 following 234 posts

Working on web performance optimization, founder of @debugbear.com

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mattzeunert.com @mattzeunert.com · 9h
Example.com just received a redesign, with JavaScript-enabled language transitions! Our latest blog posts takes a look at how the website has changed over time. www.debugbear.com/blog/example...
debugbear.com
Example.com Just Launched The Biggest Redesign In Decades | DebugBear
A look at the history of visual changes to example.com.
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mattzeunert.com @mattzeunert.com · 29/09/2026
Want to know what features are supported in your visitors' browsers? DebugBear now reports browser version adoption over time and shows you browser support based on Google's Baseline project.
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mattzeunert.com @mattzeunert.com · 28/09/2026
New in DebugBear custom dashboards: show rating thresholds for each metric, and customize your data aggregation interval.
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mattzeunert.com @mattzeunert.com · 25/09/2026
More progress on speeding up VM launches, this time by switching to a faster disk type!
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mattzeunert.com @mattzeunert.com · 18/09/2026
We finally did some more work to bring down the launch time of the VMs that run our page speed tests! VMs now start 30% faster after embedding more data in the disk image rather than loading it from artifact registry.
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mattzeunert.com @mattzeunert.com · 16/09/2026
Google has launched a new set of ad performance metrics! Our latest article takes a deeper look at how this data is collected and what you can do with it. www.debugbear.com/blog/chrome-...
debugbear.com
New Data From Google: See How Ads Impact Web Performance | DebugBear
Google has been working on new metrics to measure how ads impact performance. Learn how you can view this data for real visitors and how to check it yourself in Chrome DevTools.
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mattzeunert.com @mattzeunert.com · 15/09/2026
Google has started publishing ad performance data as part of the Chrome User Experience Report! Where available, you can now find this data in the Web Vitals tab of our free website speed test. Try it yourself here: www.debugbear.com/test/website...
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mattzeunert.com @mattzeunert.com · 03/09/2026
Interesting AI overview 💦⚽️
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mattzeunert.com @mattzeunert.com · 02/09/2026
Marketing and development teams often work on web performance problems together. In this guide I explain how different teams can collaborate effectively and get the web performance data they need. www.debugbear.com/blog/marketi...
debugbear.com
How Marketing And Development Teams Can Collaborate On Page Speed | DebugBear
Marketing owns the site experience but developers make the changes. Learn how both teams can use shared performance data, experiments, and alerts to work together on page speed.
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mattzeunert.com @mattzeunert.com · 31/08/2026
My Pixel Pioneers talk is on Youtube now! I give a brief introduction to page speed and then dive into different network throttling methods in Lighthouse, DevTools, and other tools. www.youtube.com/watch?v=KO02...
youtube.com
Where Do Your Web Performance Metrics Come From? - Matt Zeunert - Pixel Pioneers 2026
YouTube video by Pixel Pioneers
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mattzeunert.com @mattzeunert.com · 30/08/2026
Spent some time looking at carbon emission calculations for two proposed new data centers. britishequalitylab.com/p/what-are-t...
britishequalitylab.com
What are The Guardian and Foxglove saying about two proposed new data centres?
How does the emissions calculation work?
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mattzeunert.com @mattzeunert.com · 28/08/2026
We're working on updating our weekly report! It will include data across synthetic tests, CrUX, RUM, and uptime checks. Plus you'll be able to receive it in Slack and Teams, rather than just over email!
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mattzeunert.com @mattzeunert.com · 27/08/2026
Our RUM product now lets you track each soft navigation in a single page app as it's own page view! This way you can get Core Web Vitals metrics that match how your users actually experience navigating around your app. www.debugbear.com/docs/rum/spa...
debugbear.com
Single Page App (SPA) Monitoring | DebugBear
Learn how DebugBear tracks client-side navigations in single page applications and how to report each soft navigation as its own page view.
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mattzeunert.com @mattzeunert.com · 26/08/2026
New in Debugear this month: ✅ Uptime monitoring 🤖 Server timing support 🤑 URL-based conversion triggers www.debugbear.com/changelog/au...
debugbear.com
August 2026: Uptime monitoring and Server Timing support | DebugBear
Introducing Uptime Monitoring to track site availability, Server Timing support for lab tests and RUM, URL-based conversion triggers, and more customization options.
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mattzeunert.com @mattzeunert.com · 24/08/2026
Coming soon in DebugBear: track Core Web Vitals for individual soft navigations in single-page apps.
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mattzeunert.com @mattzeunert.com · 22/08/2026
Claude is great for making papers more readable. The aversion some academics have to paragraphs is bizarre.
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mattzeunert.com @mattzeunert.com · 21/08/2026
I got distracted and ended up needing over 5 weeks to finish my latest article on UK air conditioning rules 😔 But I'm finally done taking a closer look at the stories in The Telegraph and some of the broader media coverage. britishequalitylab.com/p/a-review-o...
britishequalitylab.com
A review of media reporting on air conditioning planning rules in Camden
The specific stories are true, but it's hard to draw broad conclusions
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mattzeunert.com @mattzeunert.com · 20/08/2026
Server timing headers make backend performance metrics available on the front-end. Our latest article explains how these headers work and how to view them in DevTools and DebugBear. www.debugbear.com/blog/server-...
debugbear.com
Server Timing: Measure And Track Backend Performance | DebugBear
Learn what the Server-Timing header is and how to track server-side performance metrics.
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mattzeunert.com @mattzeunert.com · 17/08/2026
We've improved support for server timing headers in DebugBear! 📊 Breakdown view in request details ⚙️ Automatic server timing tracking in synthetic monitoring 📈 Track server timings as a custom RUM metric
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mattzeunert.com @mattzeunert.com · 14/08/2026
I made a flowerpot from the soil in my friend's garden! Wasn't sure it's possible, but ChatGPT was incredibly helpful throughout the process.
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mattzeunert.com @mattzeunert.com · 13/08/2026
DebugBear now also sends out notifications when one of your web performance budgets recovers.
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mattzeunert.com @mattzeunert.com · 12/08/2026
We now show Core Web Vitals metrics for specific soft navigations in your RUM data! Note that this is currently only supported in the latest version of Chrome.
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mattzeunert.com @mattzeunert.com · 11/08/2026
New video: learn how to identify web performance bottlenecks on your website. youtu.be/yW1mVJuZ-N8
youtu.be
Find web performance bottlenecks
The DebugBear website bottleneck finder is a new free tool to help uncover issues with First Contentful Paint, Largest Contentful Paint and the H1 element. Try the tool:…
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mattzeunert.com @mattzeunert.com · 04/08/2026
A beta version of our uptime monitoring product is available now! It's free to try right now, and we appreciate any feedback.
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mattzeunert.com @mattzeunert.com · 03/08/2026
What if the browser could report performance issues like it does security issues? The Network Efficiency Guardrails API is a proposed web platform feature that detects page speed issues in the browser and sends a report to the server. www.debugbear.com/blog/network...
debugbear.com
Network Efficiency Guardrails: Detect Web Performance Issues | DebugBear
Learn how to detect hidden network performance problems before they impact your users. This guide explains Microsoft's new Network Efficiency Guardrails, how they use Document Policy and the…
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mattzeunert.com @mattzeunert.com · 30/07/2026
DebugBear product updates for July: 🍾 New free bottleneck finder 💽 Better data export 🤔 Improved comparison view 🌎 Bulk update test regions www.debugbear.com/changelog/ju...
debugbear.com
July 2026: New bottleneck finder tool and better data export | DebugBear
Introducing our new bottleneck finder tool, individual chart exports for custom dashboards, improved comparison data, bulk region editing, and HAR waterfall exports.
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mattzeunert.com @mattzeunert.com · 30/07/2026
Starting to add uptime monitoring to DebugBear! Already detected a short outage on web.dev, and brought down our uptime monitoring infrastructure for three hours 🙃
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mattzeunert.com @mattzeunert.com · 29/07/2026
New article explaining how our bottleneck finder can detect render-blocking requests that Chrome doesn't report! Learn how we built our latest free tool. www.debugbear.com/blog/website...
debugbear.com
Find Hidden Render-Blocking Requests with the Website Bottleneck Finder | DebugBear
Chrome's render-blocking label doesn't always fully illustrate which resources are impacting a page's First Contentful Paint (FCP), Largest Contentful Paint (LCP) or H1-visible metrics. We recently…
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mattzeunert.com @mattzeunert.com · 28/07/2026
We've published a new video explaining how to get started with the DebugBear MCP server and how it can help you analyze web performance issues and set up monitoring. www.youtube.com/watch?v=V8sw...
youtube.com
How to setup and use the DebugBear MCP Server
In this video, we will take a look at how to setup the DebugBear MCP Server with Claude. DebugBear MCP server guide: https://www.debugbear.com/docs/mcp 0:00 - Intro 0:38 - Setup with Claude 1:30 -…
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mattzeunert.com @mattzeunert.com · 27/07/2026
Spotted a recent performance regression on the Squarespace homepage recently: the H1 and main image now depend on a script to show up. DebugBear reports the regression right away, and you can start seeing the impact on Google's CrUX metrics as well now. www.debugbear.com/project/2597...
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mattzeunert.com @mattzeunert.com · 24/07/2026
We've made some improvements to our Website Bottleneck Finder! Thanks for all the feedback 🥰 🔬 Actionable advice 🤔 More context on how the bottleneck finder is different from our page speed test 😵 Fewer crashes Try it yourself here: www.debugbear.com/website-bott...
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mattzeunert.com @mattzeunert.com · 17/07/2026
We've just launched a new free tool: the Website Bottleneck Finder detects which resource requests hold back the FCP, LCP, and H1 rendering time! www.debugbear.com/website-bott...
debugbear.com
Website Bottleneck Finder
Find which network resources slow down page rendering. Check if your page depends on specific scripts or data.
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mattzeunert.com @mattzeunert.com · 16/07/2026
The Ministry of Housing has confirmed that developers can add air conditioning to homes that already meet the passive cooling requirements! AC could still be impracticable due to the "all possible passive means" standard, sustainability requirements, or local planning rules.
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mattzeunert.com @mattzeunert.com · 15/07/2026
We've improved the comparison view for breakdown bars in DebugBear! Instead of just showing data side by side you now get an actual comparison.
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mattzeunert.com @mattzeunert.com · 13/07/2026
Parser-blocking scripts block rendering of any content below them in the HTML. If they are placed at the end of the body then that's not a problem, but if they appear further up they can slow down your website. Learn more: www.debugbear.com/blog/visuali...
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mattzeunert.com @mattzeunert.com · 10/07/2026
UK councils don't usually require homeowners to prove their need for air conditioning with dynamic thermal modelling. However, the London borough of Camden does have extensive requirements to comply with their sustainability guidelines. britishequalitylab.com/p/camdens-an...
britishequalitylab.com
Camden's anti-air conditioning rules are unusually strict
Some Londoners need to use dynamic thermal modelling to demonstrate the need for AC
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mattzeunert.com @mattzeunert.com · 09/07/2026
These almost look like real enterprise enquiries, except for the example.net email address...
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mattzeunert.com @mattzeunert.com · 06/07/2026
Largest Contentful Paint delays in single page apps often show up as load delay. Until the JavaScript code has run, the browser simply doesn't know about the image file that it needs to load. Learn more about load delay here: www.debugbear.com/blog/lcp-res...
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mattzeunert.com @mattzeunert.com · 05/07/2026
Still confused by the new build AC ban. My naive read of Part O does not sound like a ban. Though it also interacts with Part L (reducing power use). But then the Part O impact assessment states avoiding AC uptake as a goal, not just passive cooling assets.publishing.service.gov.uk/media/61b883...
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mattzeunert.com @mattzeunert.com · 01/07/2026
I spent some time looking through UK planning applications to find out why councils don't allow air conditioning to be installed. britishequalitylab.com/p/why-do-uk-...
britishequalitylab.com
Why do UK councils refuse planning permission for air conditioning units?
Mostly due to noise
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mattzeunert.com @mattzeunert.com · 01/07/2026
Cannabis isn't banned in the UK! You just need to demonstrate need and show that you've exhausted all preferable steps of the treatment hierarchy.
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mattzeunert.com @mattzeunert.com · 30/06/2026
Our website traffic has been pretty stable over the last two years, but Ahrefs estimates we 10x'd it! I think it's a mix of spam in their data and some high-volume keywords where we rank but don't get many clicks.
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mattzeunert.com @mattzeunert.com · 29/06/2026
I finally managed to find an example where an air conditioning unit was actually removed at least partially for climate reasons! On appeal, the refusal based on local character, noise, and Camden's climate change resilience policy was upheld.
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mattzeunert.com @mattzeunert.com · 29/06/2026
Councils rarely refuse permission to install AC because of the cooling hierarchy. Normally it's due to noise or appearance. Camden Council did order the removal of three heat pumps, despite extensive prior work. On appeal, planning permission was granted.
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mattzeunert.com @mattzeunert.com · 27/06/2026
Is air conditioning banned in the UK? I spent some time looking into the factors that lead to it not being permitted. britishequalitylab.com/p/the-uk-doe...
britishequalitylab.com
The UK doesn't ban air conditioning – it doesn't permit it
The Telegraph reports that local councils are forcing homeowners to remove air conditioning units.
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mattzeunert.com @mattzeunert.com · 26/06/2026
DebugBear product updates for June: ✨ Access page speed data with our MCP server 📊 More flexible histograms 🐱 View data correlations with scatter plots 🎥 Learn how to scan your website www.debugbear.com/changelog/ju...
debugbear.com
June 2026: Custom dashboard improvements and an MCP server | DebugBear
Introducing histogram and scatter plot charts for custom dashboards, plus a new DebugBear MCP server for Claude, ChatGPT, and Cursor.
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mattzeunert.com @mattzeunert.com · 25/06/2026
Just published a new industry benchmark: how fast are different post office websites in Europe? www.debugbear.com/blog/europea...
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mattzeunert.com @mattzeunert.com · 24/06/2026
Are some government websites just slow because visitors have slower websites? To answer that question, we added support for scatter chart to our DebugBear performance dashboards!
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mattzeunert.com @mattzeunert.com · 23/06/2026
WebMCP lets websites expose tools for AI agents. @jacobandrewsky.bsky.social explains how the experimental technology works. www.debugbear.com/blog/webmcp
debugbear.com
WebMCP: Optimize Your Website for AI Agents | DebugBear
Learn how WebMCP enables AI agents to interact with websites through structured tools instead of traditional browser automation. This guide explains how WebMCP works, how it compares to DOM-based appr...
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mattzeunert.com @mattzeunert.com · 22/06/2026
You can now create custom histograms in your DebugBear dashboards! Add additional metrics to view how they correlate.
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