How We Reduced Image Loading Times by 75%

A real-world case study showing the dramatic performance improvements possible through comprehensive image optimization.

The Challenge

Our e-commerce client was experiencing slow page loads, particularly on product pages with multiple high-resolution images. Key metrics:

• Average page load time: 4.8 seconds
• Image weight: 2.4MB per page (72% of total)
• Bounce rate: 58% on mobile

Optimization Strategy

1. Format Conversion

Converted all images to WEBP where supported, with JPEG fallbacks:

<picture>
  <source srcset="image.webp" type="image/webp">
  <source srcset="image.jpg" type="image/jpeg">
  <img src="image.jpg" alt="Product">
</picture>

2. Responsive Images

Implemented srcset to serve appropriately sized images:

<img srcset="small.jpg 480w, medium.jpg 768w, large.jpg 1200w"
     sizes="(max-width: 600px) 480px, (max-width: 1000px) 768px, 1200px"
     src="medium.jpg"
     alt="Product">

3. Compression

Applied aggressive but visually acceptable compression:

• WEBP: Quality 75
• JPEG: Quality 65
• PNG: Maximum compression

4. Lazy Loading

Implemented native lazy loading for below-the-fold images:

<img src="image.jpg" loading="lazy" alt="Product">

The Results

Key Takeaways

• Format matters: WEBP provided significant savings over JPEG
• Right-sizing is crucial: Serving appropriately sized images had the biggest impact
• Compression can be aggressive: Most users didn't notice quality differences
• Performance impacts conversions: Faster pages led to more engagement and sales