Slow-loading images are the number one cause of poor website performance. Every second of extra loading time reduces conversions by 7%. Here is a comprehensive strategy to make all images on your website load faster.
Why Images Load Slowly
- Images are too large (dimensions and file size)
- Using outdated formats (large JPG or PNG when WebP would be 30% smaller)
- Not using lazy loading — all images load at once, even those below the fold
- No CDN — images served from a single server far from some users
- No caching headers — browsers re-download the same images on every visit
The Complete Fast-Image Checklist
- Audit: Run Google PageSpeed or GTmetrix — identify which images are slowest
- Resize: Use imgresizr.com to resize all images to actual display dimensions
- Compress: Apply 80–85% lossy compression to all photographs
- Convert: Convert JPG and PNG to WebP — 25–35% smaller
- Lazy load: Add loading="lazy" to all images not in the first viewport
- Responsive images: Use srcset attribute to serve appropriate sizes to different screens
- CDN: Serve images from a Content Delivery Network
- Cache: Set appropriate cache headers so returning visitors load images from cache
Quick Wins vs Long-Term Improvements
| Action | Effort | Impact |
|---|---|---|
| Resize + compress images | Low | Very high |
| Convert to WebP | Low–medium | High |
| Add lazy loading | Low | High |
| Set up CDN | Medium | High |
Start making your images load faster today — use imgresizr.com to resize, compress, and convert to WebP for free.