Hi <<First Name>>,
When I was compiling the research and articles and best practices for this edition of Speed Matters, I didn't set out to focus on connecting web performance to business value. But interestingly, many of the items below are about exactly that.
- Performance expert Harry Roberts shares a compelling finding from one of his clients: every extra second of Largest Contentful Paint (LCP) delay slashed conversions by roughly 13%
- My recent talk at WebExpo goes into detail about how to measure the business value of performance for your site
- The new Shopify RUM app lets Shopify store owners easily measure the impact of page slowdowns (and page speed-ups) on their own conversion and bounce rates
There's lots of other great stuff for you this month, including:
- The fastest news site in the US
- A definitive guide to understanding Long Animation Frames and why measuring them is crucial to optimizing your pages
- Three charts every performance and UX person should know
- 14 strategic performance tips for 2025
- And more!
What's on your mind lately when it comes to performance and usability? Hit reply and let me know!
Until next month,
Tammy
b: @tammyeverts.com
m: @tammy
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Forbes leads the Page Speed Benchmarks for US news sites
If you're anything like me, you're checking out the news more than usual these days. I took a look at our US Media Benchmarks, which tracks the home pages of top news sites, including LA Times, BuzzFeed, NPR, CNN, Washington Post, Financial Times, Bloomberg, and New York Times. (We also recently added The Onion, because sometimes we just need to have a laugh.)
I was happy to see that our friends at Forbes delivered a Largest Contentful Paint time (on a 'slow' mobile connection) of 1.39 seconds – which is within Google's threshold of 2.5 seconds. Well done!
Most of the other pages we benchmarked, however, failed to deliver optimal LCP times. In many cases, sites struggled with issues like:
- Slow blocking JavaScript and CSS
- Poorly performing custom fonts
- Excessive JS before the LCP element
Wondering how to improve LCP times for your pages? Here's everything you need to know to start measuring, debugging, and optimizing LCP.
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Connect the dots between site speed, user happiness, and your business
I do a LOT of talks about the intersection of performance, UX, and business success, and the version I gave recently at WebExpo is my favourite so far. You can watch it here.
Some important takeaways:
? "Web stress" is measurable
? It measurably affects your business, in terms of bounce rate, conversion rate, and other KPIs
? Some pages on your site matter more than others, from a site speed and UX perspective
? You need to know – and optimize – the critical rendering path for those pages (Not sure what the critical rendering path is? No worries, I explain it!)
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Correlation charts FTW!
Performance expert Harry Roberts uses a SpeedCurve correlation chart to share this insight from one of his clients: If I can get Largest Contentful Paint (LCP) under 0.8s, customers are 40% more likely to start buying than those stuck on 3-4 second pages.
Learn more:
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Easy RUM for your Shopify store
Exciting news for all you Shopify folks! Now it's easy to enable high-powered real user monitoring (RUM) in your storefront, with no coding or developer time required! With the SpeedCurve RUM app – developed by our friend and Shopify expert Sia Karamalegos – you can:
⚡ Track metrics like Core Web Vitals
⚡ Identify and fix performance issues
⚡ Measure the impact of site speed on business metrics, like conversion rate (using correlation charts!)
⚡ Fight regressions and stay ahead of page slowdowns
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The Definitive Guide to Long Animation Frames (LoAF)
Historically, the biggest issue with real user monitoring was that it captures a tonne of data, but it was hard to tease out what's actionable. The Long Animation Frames (LoAF) API is an evolutionary leap forward for RUM diagnostics, because it lets you find and fix the third parties and other scripts that hurt your page speed and user experience.
The only downside to LoAF is that it's tricky to wrap your head around. No longer! Andy Davies wrote this definitive guide to LoAF, which covers:
? Why animation frame rate matters
? Anatomy of a Long Animation Frame
? Key LoAF milestones and what to do with milestone data
? Script attribution
? How to connect LoAF and INP data
? How to get started
If you want to know how to monitor LoAF in SpeedCurve, you can learn more here.
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Building a fast website for every single visitor
In this PerformanceObserver session, Medhat Dawoud covers the principles and techniques behind adaptive design, including responsive layouts and dynamic interactions, device strengths, internet speeds, screen sizes, and user preferences. If you care about creating great experiences for all your users (and I hope you do), this talk is a good one!
If you'd like to find out about upcoming PerformanceObserver talks in advance, sign up for the newsletter.
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14 web performance tips for 2025
"What should you be worried about when it comes to web performance in 2025? How should you even start?"
Sia Karamalegos is a perfect person to answer these questions. In this very detailed post, Sia gives strategic, pragmatic advice – some of which may come as a surprise. (Example: Images are usually a micro-optimization and may not be worth the investment.)
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Pro tip: Use IDs on the most important page elements
One last tip! This one comes from our friend Joan León at Adevinta. Using meaningful IDs on your elements can make it much easier and faster to debug performance issues, such as Interaction to Next Paint!
Get more tips for debugging INP >
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