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.

1. 7 Levels of a
Web Performance
Journey
Sergey Chernyshev
Performance.sync() 2025, Amsterdam October 29, 2025

2. About Us
Eric Goldstein Sergey ChernyshevAlexander 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 desktop
1
●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:
Δ?????????????????? = ?????? × Δ?????????????????? + ?????? (?????? is the coefficient that measures the correlation between
the two values and ?????? 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 rate
3

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
PoorNeeds ImprovementGood
(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 4s2s 3s0

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!