Core Web Vitals
Performance should be evaluated using real user experience metrics. Important metrics include Largest Contentful Paint, Interaction to Next Paint, and Cumulative Layout Shift.
LCP can be affected by server response time, image loading, fonts, and rendering. INP is influenced by JavaScript execution and interaction handlers. CLS is often caused by content whose dimensions are not reserved before loading.
Do not optimize based only on local development speed. Production performance depends on real network conditions and devices.
Key Takeaways
- Measure real user experience rather than relying only on localhost.
- Reserve image and content dimensions to reduce layout shifts.
- Reduce long JavaScript tasks to improve interaction responsiveness.