Web Performance and Core Web Vitals
What actually makes a page feel fast: LCP, CLS, and INP, the Network tab and bundle size, and the fixes that move the numbers.
- Perceived Performance and the Three Vitals Performance is what the user feels, not what a server log says. The three Core Web Vitals — LCP, CLS, and INP — turn loading, visual stability, and responsiveness into numbers you can chase.
- Measuring What Users Feel Lab versus field data, why Lighthouse and real users disagree, and how to read the Network tab to see where the time and the bytes actually go.
- The Levers That Move the Numbers The fixes that pay: bundle size and code splitting, image optimization, caching and a CDN, killing render-blocking resources, and sizing media so the layout stops jumping.