Introduction

In today’s fast-paced digital world, website speed isn’t just a luxury — it’s a necessity. Slow-loading pages frustrate users, hurt SEO rankings, and directly impact conversions. Among the biggest culprits of sluggish performance? Unoptimized images. In this blog, we’ll discuss how image optimization improves three critical performance metrics — FCP, LCP, and TTFB — and share actionable strategies to supercharge your site.

1. Understanding Core Web Vitals: FCP, LCP, and TTFB

What Are These Metrics?

FCP (First Contentful Paint): The time it takes for the first text or image to appear on the screen.

LCP (Largest Contentful Paint): The time it takes for the largest visible element (often an image or video) to load.

TTFB (Time to First Byte): The time between the browser’s request and the first byte of data from the server.

Why Do They Matter?

Google uses these metrics to evaluate user experience. Poor scores can hurt SEO rankings and user retention.

2. How Images Affect Performance

Images make up a significant portion of a web page’s size. Poorly optimized images can:

• Delay FCP by slowing down initial content rendering.

• Increase LCP if the largest image is too large or unprioritized.

• Worsen TTFB due to excessive server requests.

3. Optimizing Images for Better FCP

• Use Modern Formats: Convert JPEG/PNG to WebP or AVIF for smaller file sizes.

• Resize Images: Serve appropriately sized images for different devices.

• Preload Critical Images: Prioritize loading key visuals.

Example: Switching to WebP reduced our hero image size by 60%, improving FCP by 1.2 seconds.

4. Improving LCP with Image Optimization

• Compress Images: Use tools like Squoosh or ImageOptim to reduce file size.

• Use a CDN: Serve images from a Content Delivery Network to reduce latency.

• Prioritize LCP Elements: Optimize the largest visible element (e.g., a hero image) first.

Pro Tip: Use fetchpriority="high" for your LCP image to speed up loading.

5. Reducing TTFB Through Image Optimization

• Enable Caching: Cache images to reduce repeated server requests.

• Optimize Server Settings: Use efficient image compression at the server level.

• Avoid Redirects: Host images locally or on a CDN to minimize delays.

Example: Moving images to a CDN reduced TTFB from 800ms to 200ms

6. Essential Tools for Image Optimization

• Squoosh: Compress and convert images in-browser.

• ImageKit or Cloudinary: Automate resizing, compression, and CDN delivery.

• Lighthouse: Audit performance and identify image-related issues.

• WebPageTest: Test how images affect FCP/LCP across regions.

7. Quick Checklist for Image Optimization

1. Convert images to WebP/AVIF.

2. Resize images to match display dimensions.

3. Lazy load non-critical images.

4. Serve images via a CDN.

5. Set caching headers for images.

Conclusion

Optimizing images is a simple yet powerful way to improve FCP, LCP, and TTFB, ensuring faster load times and better user experiences. Start by auditing your site’s images, applying these tips, and measuring the results.

That is all for this blog, See you all in my next blog
If you have any questions or comments, please drop them below.