Web Performance: Core Web Vitals optimization

Need to improve Core Web Vitals scores (LCP, FID/INP, CLS) for better user experience and SEO.

Optimization strategies for each metric:

LCP (Largest Contentful Paint) < 2.5s:

• Preload critical resources: <link rel='preload' as='image' href='hero.webp'>
• Use responsive images with srcset
• Inline critical CSS, defer non-critical
• Server-side render above-the-fold content
• Use CDN for static assets

INP (Interaction to Next Paint) < 200ms:

• Break long tasks with scheduler.yield() or setTimeout(0)
• Use requestIdleCallback for non-urgent work
• Minimize main thread JavaScript
• Debounce/throttle event handlers
• Use CSS transitions instead of JS animations

CLS (Cumulative Layout Shift) < 0.1:

/* Always set dimensions on images/video */
img, video { width: 100%; height: auto; aspect-ratio: 16/9; }

/* Reserve space for dynamic content */
.ad-slot { min-height: 250px; }

/* Avoid inserting content above existing content */
/* Use transform animations instead of layout-triggering properties */

Measure: web-vitals library or Lighthouse CI in your pipeline.

Core Web Vitals directly impact user experience and Google search ranking. LCP measures loading, INP measures responsiveness, CLS measures visual stability.

Web applications needing performance optimization