Performance.sync(): 7 Levels of a Web Performance Journey

The path to understanding the data around Web Performance, its value and business decisions surrounding this topic can be long. It is hard to see the whole journey when you and your organization are at any particular step, but it can be helpful to understand where to go next.

Sergey Chernyshev visualizes this path to help make it more understandable and to give you some bearings on your overall trip through various levels of this complex game.

Transcript

1. 7 Levels of a Web Performance Journey Sergey Chernyshev Performance.sync() 2025, Amsterdam October 29, 2025
2. About Us Eric Goldstein Sergey Chernyshev Alexander Chernyshev Principal Engineer @ Babbel Speed Engineer @ Cloudflare Web Developer & Designer
3. Engineering focus: Speed Getting Up to Speed Business focus: Revenue Combine Focus to Create Performance Culture
4. What Matters to My Business? Total Traffic Conversion Rate Order Size Level 1 Conversion Rate origins: performance, presentation quality, SEO, availability, etc.
5. Is My Site Fast or Slow? 10% 5% Which site is faster? Level 2
6. Examples of Perf/Revenue Improvements • ALDO – an online shoe retailer – found that fast rendering brought over 4x more revenue than slow rendering for mobile users and almost 7x more for desktop1 • Ray-Ban, Oakley, & Sunglass Hut – online sunglasses retailers – saw a direct, inverse relationship between Largest Contentful Paint and Cost-per-Click via Google Ads. In other words, as LCP improved, ads got cheaper, or as LCP got worse, ads got more expensive. They even established an equation between the two: Δ𝗖𝗣𝗖 = 𝗸 × Δ𝗟𝗖𝗣 + 𝗾 (𝗸 is the coefficient that measures the correlation between the two values and 𝗾 represents external variables like Ad quality and competition)2 • Swappie – a refurbished phone retailer – improved load time by 23%, LCP 55%, CLS 91%, and FID 90% resulting in a 42% increase in mobile revenue and a 10 percentage point increase in relative mobile conversion rate3 1) https:/ /wpostats.com/2020/05/27/aldos-revenue-rendering/ 2) https:/ /www.linkedin.com/posts/daniele-merola-2a531839_webperformance-performancemarketing-ux-activity-7338097683078774784-KYM9/ 3) https:/ /wpostats.com/2021/09/16/swappie-revenue-increase/ Level 2 https://wpostats.com/
7. How Fast is My Site? 3.4 seconds Poor Needs Improvement Good (the time it takes to do one important thing) Level 3 Core Web Vitals https://web.dev/articles/vitals
8. Percentile Level 4 3.4 seconds
9. Percentile Level 4 3.4 seconds
10. Percentile Level 4 3.4 seconds
11. Percentile P75 Level 4 3.4 seconds Core Web Vitals https://web.dev/articles/vitals
12. Plot percentile over time Mar 14 Mar 15 Mar 16 Mar 17 Mar 18 Mar 19 Mar 20 Level 5
13. 3 percentiles over time P99 P75 P50 Mar 14 Mar 15 Mar 16 Mar 17 Mar 18 Mar 19 Mar 20 Level 5
14. Speed Distribution Level 6 P75 P50 P99 3.4s 1s 4s 2s 3s 0
15. Compare distributions Level 7
16. Correlate Distribution to $$$ Level 7 Cliff Crocker - Conversion over speed distribution chart
17. Going Further… Next >
18. Going Further… Next >
19. UX Speed Calculator https://ux-speed-calculator.netlify.app/
20. Sergey Chernyshev www.SergeyChernyshev.com Thank You!