Images account for the majority of bytes downloaded on most web pages. Optimizing them is one of the most effective ways to improve performance.
Modern Image Formats
WebP
WebP provides superior compression compared to JPEG and PNG:
- 25-35% smaller than JPEG
- Supports transparency like PNG
- Excellent browser support (95%+)
AVIF
The newest format with even better compression:
- 50% smaller than JPEG
- Better quality at same file size
- Growing browser support
Responsive Images
Use the srcset attribute to serve different image sizes:
<img
src="image-800.jpg"
srcset="image-400.jpg 400w, image-800.jpg 800w, image-1200.jpg 1200w"
sizes="(max-width: 600px) 400px, (max-width: 1000px) 800px, 1200px"
alt="Optimized responsive image"
/>
Lazy Loading
Load images only when needed:
<img src="image.jpg" loading="lazy" alt="Lazy loaded image" />
This native browser feature delays loading off-screen images.
Compression Techniques
- Lossy compression: Reduce quality slightly for smaller files
- Lossless compression: Optimize without quality loss
- Progressive JPEGs: Load incrementally for perceived speed
Image CDNs
Image CDNs automatically optimize and serve images:
- Automatic format conversion
- Dynamic resizing
- Global edge caching
- Real-time optimization
Conclusion
Image optimization is crucial for web performance. Implement these techniques to dramatically reduce page load times.
Try TheWebBooster for automatic image optimization without the hassle.
