Images account for the majority of data downloaded when a web page loads. According to data from the HTTP Archive, the median web page transfers over 1MB of images — and many pages transfer 3–5MB or more. Compressing your images is the single highest-impact action you can take to improve website loading speed, Core Web Vitals scores, and ultimately, search rankings.
How Images Affect Website Speed
Google's Core Web Vitals include Largest Contentful Paint (LCP) — which measures how long the main image or content block takes to load. If your hero image or featured image is uncompressed, it will directly hurt your LCP score. A page that loads in under 2.5 seconds gets a "Good" LCP; most unoptimised pages with large images fail this threshold on mobile connections.
| Action | Speed Improvement |
|---|---|
| Compress images (JPG 75%) | 50–70% smaller |
| Convert to WebP | Additional 25–35% smaller |
| Resize to correct dimensions | Prevents over-downloading |
| Enable lazy loading | Defers off-screen images |
The Correct Image Compression Workflow
- Resize first — scale images to the maximum display width, e.g. 1200px for blog posts.
- Compress second — use the Image Compressor at imgresizr.com at 75–80% quality.
- Convert to WebP — use the Converter for an additional 25–35% reduction.
- Test with PageSpeed Insights — run your URL through Google PageSpeed Insights to confirm the improvement.
Additional Speed Optimisation Tips
Use Lazy Loading
Add loading="lazy" to all <img> tags below the fold. This tells the browser not to download images until they're about to scroll into view, dramatically reducing the initial page load payload for pages with many images.
Use a CDN for Image Delivery
A Content Delivery Network (CDN) serves your images from servers geographically close to each visitor. This reduces latency, especially for US and UK audiences visiting international websites. Most major hosting platforms (Cloudflare, Vercel, Netlify) include CDN functionality automatically.
Compress Images for a Faster Website
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