Question 1

How to measure Core Web Vitals in production?

Accepted Answer

Use the Web Vitals library or tools like Perfume.js for real-user monitoring. The project provides links to polyfills for older browsers and code snippets for implementing metrics like FID and LCP.

Question 2

What's the difference between lab data and field data for web performance?

Accepted Answer

Lab data comes from synthetic tools like Lighthouse in controlled environments, while field data is collected from real users via RUM. The project explains this in the Concepts section and lists tools for both approaches.

Question 3

Lighthouse vs WebPageTest: which is better for performance testing?

Accepted Answer

Lighthouse is great for integrated Chrome audits and quick insights, while WebPageTest offers more configurable tests and real browser instances. The project lists both without bias, helping you decide based on your testing needs.

Question 4

How to reduce Cumulative Layout Shift (CLS) on my website?

Accepted Answer

Optimize images with explicit dimensions, avoid inserting content dynamically, and use CSS transforms. The project links to the CLS spec and web.dev docs for detailed implementation tips.

Question 5

Can I use Google Analytics for performance tracking?

Accepted Answer

Yes, with custom setup using the Performance Timing API. The project references a blog post by Philip Walton on how to implement performance tracking with Google Analytics.

Question 6

What tools are best for real user monitoring (RUM)?

Accepted Answer

Options include SpeedCurve LUX, Akamai mPulse, and open-source libraries like Perfume.js. The project lists these with brief descriptions, but you'll need to evaluate based on your budget and requirements.

PageSpeed Metrics

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