What is the critical rendering path of your website, and how do you optimize it? My new video explains how browsers load key resources needed to display page content and how to use the Lighthouse network dependency tree to analyze request chains. www.youtube.com/watch?v=Yf4i...

We've improved the request initiator snippets we collect, as well as formatting them more nicely! Give it try with our free website speed testing tool: debugbear.com/test

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...

Was looking for something else and ended up stumbling upon bear-evolution.sketch...

Product updates for December: 🚨 Better RUM + synthetic alerts 📊 View request statistics 💰 Track session duration 🎥 Videos on DevTools throttling + fetchpriority www.debugbear.com/changelog/de...

Had a memory leak for a few years and just kinda ignored it... finally figured out what it was: we were using lodash memoize without ever clearing the cache!

Buying a train ticket in Germany 🇩🇪

Still a lot more work to do, but I've started tidying up the design of our alert emails!

We finally got the SOC 2 report from our auditor 🎉 Was putting SOC 2 off for a while, but earlier this year we put in place all the necessary controls and went through the audit process. Learn more in our trust center: trust.debugbear.com

Spent some time tidying up our free test landing page!

🤔 What are request priorities, and why do we even need the HTML fetchpriority attribute? Check out my new video to find out! www.youtube.com/watch?v=yoa7...

We've made so much progress on DebugBear over the last year! 📈 Better real user monitoring reports 📊 More in-depth synthetic data 👫 Improved team collaboration www.debugbear.com/blog/debugbe...

Our new system for RUM alerts is live! 📈 View alert history over time 📊 Only alert on consecutive breaches 😌 Share alert conditions between email and Slack alerts Learn more: www.debugbear.com/docs/rum/ale...

Why would a render-blocking CSS file be this big? It's not just the 33 embedded fonts! The stylesheet contains over 37,000 rules, many with extremely long selectors. Ultimately 20% of visitors wait more than 4 seconds for the page to load. Test your own website: www.debugbear.com/test/website...

Last week Safari added support for the Largest Contentful Paint and Interaction to Next Paint metrics. Read my new blog post to learn what this means for measuring performance for real users. www.debugbear.com/blog/firefox...

I took a look at Core Web Vitals on the Splunk homepage. Learn how content hidden by anti-flicker snippets, tracking scripts slowing down interactions, and large images embedded in the HTML impact user experience. www.debugbear.com/blog/splunk-...

Do I know anyone who could write an article on ecommerce SEO for the DebugBear website? Something general, but probably with a focus on technical SEO.

Throttling the network in Chrome DevTools might not do what you think it does! Depending on how the network is throttled you'll see different loading behavior and different metrics. www.youtube.com/watch?v=93HI...

Want to optimize images in your Next.js app? Our new guide explains how to use the <Image> component and optimize it for performance. www.debugbear.com/blog/nextjs-...

🥱 How can lazy loading below-the-fold images speed up your website? Browsers often can't correctly prioritize images when loading a page. Content for a footer image might arrive before the main image. Deferring offscreen images fixes that. www.youtube.com/watch?v=CPJf...

🚀 What was new in web performance in 2025, and what changes are coming up next year? Read our annual review post to find out! www.debugbear.com/blog/2025-in...

The Pingdom website speed test is extremely popular. But is it always that helpful? There are a few key limitations like older metrics, an unthrottled connection, and performance recommendations without much detail. www.youtube.com/watch?v=2KMw...

Added a new request stats view to the DebugBear page speed test result! Try it for free here www.debugbear.com/test/website...

Woo boy - some of the examples in this post! www.debugbear.com/html-size-an... is nice solution to identify this though!

🎄 I wrote about HTML document size for the web perf advent calendar! Learn how embedded images, data, and fonts can lead to large HTML downloads! calendar.perfplanet.com/2025/explori...

Images that appear off-screen can delay above the fold content. Lazy loading these images can improve your page speed. The video shows a website where that's the case. I used the DebugBear "Lazy load offscreen images" experiment, and the Largest Contentful Paint metric improved by over 50%!

When I looked at the Calendly booking page last week, one thing that was slowing it down was a device fingerprinting script. These are sometimes used for security reasons, but they often run resource-intensive code, in this case a WebAssembly script. Full audit: www.debugbear.com/blog/calendl...

Claude used to be so good at fixing typos and grammar, but it's now become totally obsessed with making punctuation tweaks I have to review.

Sometimes I look at DebugBear screenshots from earlier this year and I'm shocked how much progress we've made on our design! It didn't feel that bad to me a the time, but there were a lot of harsh colors and grays, too much information stuffed into each screen.

Found a CSS file with 32,000 rules. Plus all of those are also embedded in the JS bundle 🤯 Would be a lot smaller if served with Gzip or Brotli compression too!

Doing some work to support more advanced alert conditions for DebugBear web performance monitoring 🙂

Recently fixed a layout shift on our website: when our app rendered the header nav became a tiny bit taller. Not a big shift, but it did impact all other page content, resulting in a high Cumulative Layout Shift score. Learn more about debugging layout shifts: www.debugbear.com/docs/metrics...

Just published a real-world performance audit on the Calendly booking page. Discovered some issues related to CSS size as well as JavaScript rendering. Read the full article: www.debugbear.com/blog/calendl...

New free tool: check website SEO including the Lighthouse score, Open Graph data, and heading elements. www.debugbear.com/website-seo-...

Did you know website features like accordions and modals can be implemented without JavaScript? @aarontgrogg.com talked about reducing JS usage with modern browser features at last week's PerformanceObserver meetup. www.youtube.com/watch?v=R6AE...

Prioritizing some resources on a website often comes at the cost of others. For example, if you preload many images to make them show up quickly, that can delay render-blocking stylesheets or scripts from loading.

The recording from my PerformanceObserver presentation is up! Learn about tight mode, simulated throttling, Netlog data, and more! www.youtube.com/watch?v=MjiJ...

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...

Talking to @henrihelvetica.bsky.social about web performance in a bit over an hour!

Why would a browser create a second connection to the same server, even though HTTP/2 can handle multiple requests on one connection? It's because some requests are credentialed, while others are sent without including cookies or authentication headers.

I'm speaking at the PerformanceObserver online meetup tonight! Learn about performance testing, netlog data, credentialed requests, tight mode, HTTP priorities, and more! performanceobserver.dev/events/episo...

We've started working on a conversion tracking feature for DebugBear! Measure how web performance is impacting visitor behavior and conversion rates. www.debugbear.com/docs/rum/con...

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...

👴 Back in my day when you told the computer to do something it just did it. No code formatters or pre-commit hooks putting you on hold for 10 seconds!

The DebugBear request waterfall back when it was still built on top of Highcharts 😂

Recently a customer was telling me no analytics data was reported for one of their websites. I used the script below to find the culprit: a script in Google Tag Manager that assigned a different navigation value! Learn about other JavaScript debugging techniques: www.debugbear.com/blog/chrome-...

Our JSON Size Analyzer now can now identify images embedded in your JSON code! Spotted an example yesterday where 42 images were part of the JavaScript hydration state. Test your JSON here: www.debugbear.com/json-size-an... Or check HTML and embedded scripts: www.debugbear.com/html-size-an...

Recorded a video explaining how to use WebPageTest and interpret the request waterfall! www.youtube.com/watch?v=vdpq...

What's a good strategy to speed up your website? And how should you respond to different types of regression alerts? My new article explains the role of monitoring and different types of performance data for website optimization. www.smashingmagazine.com/2025/11/effe...

Then, @mattzeunert.com will walk us through Synthetic Web Performance testing with @debugbear.com. All details and add-to-calendar (with zoom link) at performanceobserver.dev 🕒 Wed Nov 19 at 6 PM CET / 5 PM GMT / 12 PM ET / 9 AM PT (🧵 2/2)