How to Reduce a Website’s Carbon Footprint and Improve Performance (Case Study)

Invisible optimization refers to technical improvements that increase website performance, energy efficiency, and SEO without modifying the visual interface.

Typical benefits include:

• Faster loading times
• Lower CO₂ emissions
• Better SEO rankings
• Improved mobile performance
• Higher conversion rates

These gains are achieved through backend optimizations such as font hosting, image compression, caching, and code cleanup.

When fonts are loaded from third-party servers, each page visit generates additional HTTP requests, increasing:

• latency
• bandwidth usage
• carbon emissions

By downloading the fonts and serving them directly from the website’s server, we eliminate those external calls.


Best practices for font optimization :

• Download fonts directly from Google Fonts or other providers
• Convert files to WOFF2, the most efficient web font format
• Limit the number of fonts to two families maximum
• Use only the necessary font weights

Most website builders such as WordPress, Webflow, and Wix allow you to upload custom fonts easily.

Result: smaller page size, faster loading, and reduced carbon footprint — with no visual change to the design.

Images are often the largest contributors to page weight, which makes them a critical optimization target.
We improved image efficiency using two techniques:

1. Modern image formats

We converted images to WebP, which typically reduces file sizes by 25–50% compared to JPEG or PNG while preserving visual quality. In some cases, AVIF can reduce size even further.

2. Smart compression

We then compressed images using tools such as:

• ImageOptim
• TinyPNG
• Squoosh

Our workflow is simple:

• Keep the original image as a reference.
• Compress the file progressively.
• Compare visually until a difference becomes noticeable
• Use the highest compression level that preserves quality.

In many cases, this process cuts image weight in half without any visible degradation.

Result: reduced data transfer, lower energy consumption for servers and devices, and faster page loads.

Another major improvement came from better cache configuration and removing unnecessary assets.

Caching allows browsers to store static resources locally, preventing them from being downloaded again on every visit.

Key caching improvements :

• Minifying CSS and JavaScript
• Enabling lazy loading for images
• Setting proper Cache-Control headers
• Deferring non-critical scripts

These optimizations reduce network requests and processing time, especially for returning visitors.

Removing unnecessary plugins

Many websites accumulate plugins and modules over time, including:

• duplicate analytics scripts
• unused libraries
• outdated plugins

Removing these unnecessary components reduces page weight, server processing and security risks.

Result: a lighter, faster, and more maintainable website.

Improving a website’s performance does not mean sacrificing design or creativity. In many cases, the most impactful improvements happen behind the scenes. By hosting fonts locally, optimizing images, improving caching, and removing unnecessary plugins, it is possible to significantly reduce a website’s carbon footprint while making it faster and more efficient.

In this case study, these invisible optimizations led to concrete improvements: mobile performance increased by 30% and the website’s EcoGrade improved from C to A, all while keeping the same design, same content, and the same brand identity. From the user’s perspective, nothing changed visually — the experience simply became faster and smoother.

This illustrates an important principle of sustainable web design: small technical adjustments can create meaningful impact. They improve SEO rankings, enhance user experience, reduce bounce rates, and lower the environmental footprint of digital services. A lighter website ultimately benefits everyone — your users, your business, and the planet. 🌍