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Optimization can reduce transferred data and repetitive work. Check its effect on performance; any environmental result should be estimated with a defined method and reference scenario.
At Replanta, we check that, with small technical actions, it is possible to reduce the total size of a website by up to 40% without sacrificing design or content.
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Here we share the 7 most effective steps to achieve it.1.
Audit the initial weight of your website. Before optimizing, you need to know how much does your website weigh currently?.
There are free tools that give you a clear view:
| Tool | What it measures | Link |
| PageSpeed Insights | Total size, Core Web Vitals, speed | https://pagespeed.web.dev |
| GTmetrix | Weight of each resource (images, scripts, CSS) | https://gtmetrix.com |
Note the total weight in MB, the number of requests and the main problem areas (images, videos, JS, CSS, fonts). This diagnosis will be your baseline to measure progress.
2. Optimize your images (70% of the average weight)
Images are the biggest contributors to the weight of a website. Fortunately, it is the area where you can reduce the most without losing quality.
Best practices:
- Convert to modern formats like WebP or AVIF (40–60% lighter).
- Resize before uploading: don’t upload a photo of 4000px if it is only displayed at 1200px.
- Compress with tools like TinyPNG, Squoosh, or ShortPixel.
- Lazy loading: images outside the viewport are only loaded when scrolling.
If you use WordPress, we recommend the plugin OptimoleImagify or EWWW Image Optimizer.
Tip: if you want to know more options to optimize your images read our article Image Optimization and Other WPO Techniques in WordPress
3. Use lightweight videos or eco-friendly embeds
Videos can increase the weight of a page. To reduce it, follow these recommendations:
- Avoid autoplay and unnecessary resolutions.
- Upload to external platforms (YouTube, Vimeo) but use lite embeds (light loads).
- Optimize thumbnails : a static initial image is enough.
- Disable unnecessary tracking scripts.
Tip: If the video does not provide direct value to the conversion or understanding of the content, it’s better to link it outside the page.
Also read: Sustainable media: images and video that do not destroy speed
4. Check your fonts (local or system fonts)
External fonts can add up to 200 KB or more to your website’s weight.
Each variant (bold, italic, light, etc.) implies an additional file.
What to do:
- Host the fonts locally (download them to your server).
- Load only the variants you use.
- Consider using system fonts. (like Arial, Roboto, or Inter) for an ultra-light web.
This reduces requests, improves speed, and decreases energy consumption of rendering.
5. Minify and combine CSS / JS
Each additional CSS or JavaScript file implies a trip between server and browser.
A key practice to reduce total weight is to minify and combine.
- Minify: removes spaces and comments from the code (using Autoptimize or LiteSpeed Cache).
- Combine: groups small files to reduce HTTP requests.
- Deferred loading: uses defer or async on non-essential scripts.
- Disable unnecessary libraries: each extra plugin can add hundreds of KB.
If you use WordPress, consider lightweight plugins like Asset CleanUp or Perfmatters to deactivate scripts per page. At replanta we use LiteSpeed Web Cache Plugin.
6. Enable caching and use a CDN
Caching allows your website not to regenerate completely on each visit, reducing server load and energy consumption.
- Enable browser and server caching (LiteSpeedWP RocketW3 Total Cache.
- Set up the cache and, when useful for your site, a CDN. Cloudflare claims to cover its electricity consumption with renewable energy purchases; that information pertains to its network and not the origin server.
- Set up a TTL (time-to-live) reasonable (between 1–7 days for static resources).
This speeds up content delivery and drastically reduces the perceived weight for the user.
7. Measure again (before and after)
Once the improvements have been applied, measure again. Compare your results with the initial metrics:
| Metric | Before | After | Improvement |
| Total weight | 3.2 MB | 1.8 MB | -44% |
| Requests | 145 | 92 | -36% |
| LCP | 3.4s | 1.9s | +44% |
Document your own results before and after optimization. Performance changes do not alone equate to verified environmental reduction.
Supplement with our guide to optimize your website’s resources and performance.
The environmental impact of a lightweight website
Reducing the weight of files decreases the data needed to transfer them. Check performance and estimate any effect on emissions separately.
Visit emissions are estimates that depend on the data and the model used. There is no universal figure or guaranteed percentage of savings. To compare results, keep the version of the model, the input data, the period, and an equivalent reference scenario.
Being digitally sustainable is an opportunity to align your ecological values with your online presence, and also improve your SEO, conversion, and retention metrics.
Quick checklist: 7 steps to reduce the weight of your website
- Audit your initial weight with PageSpeed or GTmetrix
- Optimize images (WebP/AVIF + lazy loading)
- Use lightweight videos or deferred embeds
- Local or system fonts
- Minify and combine CSS/JS
- Enable cache + CDN
- Measure results with Website Carbon or EcoGrader
Download the Sustainable Web Checklist (PDF) to apply these improvements step by step.
Are you an NGO or eco project?
At Replanta we offer a Solidarity Plan with special conditions for purpose-driven organizations:
- Nonprofit discount
- Free initial audit (30 min)
- Sustainable optimization and migration
Request your solidarity plan here or write to us to receive a free audit of your website.
Related readings
- How to optimize your website: resources, performance, and documentation
- Measuring the digital footprint of your website
- Accessibility + performance: 30-minute changes that your users notice
- What is web eco-design and how to apply it in your WordPress step by step
