Core Web Vitals optimization for OpenCart

Core Web Vitals Optimization

LCP (Largest Contentful Paint) - 4.2s → <2.5s:

• Lazy load images: loading="lazy"
• WebP format for images
• CDN for static files
• Preload critical resources

FID (First Input Delay) - 180ms → <100ms:

• Defer JS loading: defer
• Minimize JavaScript
• Remove unused code

CLS (Cumulative Layout Shift) - 0.25 → <0.1:

img {
  width: 100%;
  height: auto;
  aspect-ratio: 16/9;
}

• Reserve space for banners
• Avoid dynamic content at top

Result: After optimization my store got green PageSpeed scores!