Images account for nearly 60% of the bytes downloaded on an average web page. Optimizing them is the single most effective way to improve performance.
1. Next-Gen Formats: AVIF vs WebP
While WebP has become the standard, AVIF offers superior compression efficiency. It uses the AV1 codec to deliver images that are 50% smaller than JPEG and 20% smaller than WebP without quality loss.
2. Responsive Images
Using the `srcset` and `sizes` attributes ensures that mobile users don't download 4K desktop images. This is critical for LCP (Largest Contentful Paint) scores.
3. Lazy Loading
Native lazy loading (`loading="lazy"`) is now supported in all major browsers. It defers the loading of off-screen images until the user scrolls near them.