How to Optimize CMS Images for Web Performance
IntermediateQuick Answer
TL;DR
Serve images in modern formats (WebP or AVIF), compress to around 80% quality, resize to actual display dimensions, add responsive `srcset` attributes, and lazy load below-fold images. Use your CMS's image transformation API to automate this rather than manually processing every upload. Images are typically the largest contributor to page weight — optimizing them has the highest performance ROI.
Key Takeaways
- WebP reduces file size ~30% vs JPEG; AVIF reduces it ~50% — serve modern formats automatically
- Always resize images to their display dimensions — never serve a 3000px image in a 400px slot
- Lazy load any image not visible on initial page load using the native `loading="lazy"` attribute
- Use `srcset` and `sizes` to serve appropriately sized images for each viewport width