Welcome to the wonderful world of web performance, where every millisecond counts and Fasterize has been the master for over 14 years. If you are an e-commerce manager or a CRO (Chief Revenue Officer), this article is for you. Our goal? To share valuable insights and practical optimizations to ensure your site loads at lightning speed and your users are delighted.

Part 1: Improving Core Web Vitals

Let's start with the basics, or should I say the fundamentals. Google's Core Web Vitals are like the Three Musketeers of web performance: LCP, INP, and CLS.

  1. Largest Contentful Paint (LCP): Loading Performance
    • Why it matters: Google recommends that LCP occurs within the first 2.5 seconds of the page starting to load. A good LCP reassures your users about the relevance of your content.
    • Optimization: Improve server response times, prioritize loading of critical resources.
  2. Interaction to Next Paint (INP): Interactivity
    • Why it matters: An INP under 200 milliseconds is recommended to ensure a good user experience. After all, no one likes waiting for a site to respond to clicks.
    • Optimization: Minimize JavaScript size, and optimize long tasks by splitting them. Google observed a 10% increase in conversions by reducing the INP of its search pages​​.
  3. Cumulative Layout Shift (CLS): Visual Stability
    • Why it matters: A CLS under 0.1 is crucial to avoid unexpected layout shifts that can frustrate your users.
    • Optimization: Reserve space for images and iframes, load fonts asynchronously, set width and height attributes on images. A Deloitte study showed that reducing CLS improves user satisfaction by 15%​​.

Part 2: Optimizing Responsive Images

Ah, images! They beautify our sites but can also significantly slow them down. Here's how to tame them.

  • Modern Formats: Use formats like WebP and even better AVIF that offer better compression without sacrificing quality. A Google study showed that using WebP reduces image size by 25-34%​​.
  • srcset attribute: Load images based on screen resolution, container size and device densitu to optimize display and load times.
  • Lazy-loading: Defer loading off-screen images to speed up the initial page load. Pinterest reduced perceived load times by 40% thanks to lazy-loading.

Part 3: Reducing Unused Resources

Unused resources are like extra weight on a sprinter. Let's shed it!

  • Resource Audit: Identify and eliminate unused CSS and JavaScript. According to an HTTP Archive study, 50% of CSS and JS files loaded by websites are never used​​.
  • Conditional Loading: Load scripts and styles only when necessary.
  • Minification and Compression: Reduce the size of CSS and JavaScript files to speed up loading. Shopify saw a 20% increase in site speed after minifying its CSS files.

Part 4: Using Content Delivery Networks (CDN)

CDN, or how to teleport closer to your users for an ultra-fast experience.

  • Why it matters: CDN reduce latency and improve resource availability. Akamai showed that CDN can reduce page load times by an average of 50%​​.
  • Optimization: Properly configure your CDN to maximize load time benefits. According to Cloudflare, a well-configured CDN can increase conversion rates by 20%.

Part 5: Advanced Techniques for Faster Pages

For those who love challenges and want to go further, here are some advanced techniques.

  • Caching Static Resources: Ok, it’s not an advanced technique but when we can see that even this basic one is not often implemented, we decided to label it as “advanced”. Use browser caching to store frequently used resources. You can also rely on bfcache when possible. A Yahoo study shows that caching can reduce load times by 40-60% for returning users​​​​.
  • Preloading Critical Resources: Preload essential files so the browser retrieves them as soon as possible. Airbnb improved its homepage load speed by 25% with this technique.
  • Speculation rules: The new Speculation Rules API in browsers allows developers to define resources that should be preloaded or prefetched, enhancing page loading speed and improving the user experience. By specifying these resources, the browser can make informed decisions about preloading assets, thereby reducing latency and ensuring faster content delivery.

Part 6: Continuous Monitoring of Web Performance

You can only improve what you measure. Time to bring out the tools.

  1. Synthetic Monitoring (Active Monitoring): Measures performance under controlled conditions.
    • Examples of tools: WebPageTest, SpeedCurve, PageSpeed Insights.
    • Advantages: Repeatable tests, identification of issues for specific user segments.
    • Data collected: Waterfall, filmstrip, UX metrics (Speed Index, Start Render, Core Web Vitals).
  2. Real User Monitoring (RUM): Measures performance based on real user data.
    • Examples of tools: Google Analytics, Treo, Rumvision, Speedcurve
    • Advantages: Continuous analysis, accounting for the diversity of users and browsing conditions.
    • Data collected: Navigation Timing, Resource Timing, User Timing, conversion rates.

Part 7: Leveraging the Edge innovation with Edgespeed

In the realm of web performance, adopting cutting-edge technologies can offer significant advantages. This is where Edgespeed comes into play, a robust solution designed to elevate your site's performance to new heights.

Why Edgespeed Matters

Edgespeed by Fasterize is your web performance ally that combines the power of edge computing with smart optimization techniques. EdgeSpeed is the unique solution that aggregates, coordinates, and organizes all web performance optimization techniques. Our intelligent engine instantly optimizes your code and all your resources. Your web performance is enhanced, and your teams are freed up! It reduces latency, improves load times, and ensures a smoother user experience.

Key Benefits of Using Edgespeed

  1. Improved Load Times in Record Time: From the moment it's connected, Edgespeed significantly reduces your site's load time. No more spending months developing and optimizing your code. EdgeSpeed does it for you continuously. 
  2. Fine-Tuned Web Performance Management: With Edgespeed, you control your web performance from your dashboard, enabling you to activate/deactivate and configure each optimization in detail. Finally, you have a tool to manage your web performance effectively. 
  3. Scalability: As your e-commerce site grows, Edgespeed effortlessly scales to accommodate increased traffic and data demands. This scalability ensures consistent performance during peak times, such as sales events or holiday seasons. 

Real-World Impact

Implementing Edgespeed leads to tangible improvements in your website's performance metrics. Faster load times translate into better Core Web Vitals scores, improved search engine rankings, and ultimately, higher conversion rates. According to studies, a 100-millisecond improvement in load time can boost conversion rates by 7%, making Edgespeed a crucial investment for e-commerce success.

By integrating Edgespeed into your web performance strategy, you can ensure that your website is not only fast and reliable but also ready to meet the demands of modern web users. Embrace the future of web performance with Edgespeed and stay ahead of the competition.


In summary, optimizing web performance is not just a best practice; it's a necessity in the ultra-competitive e-commerce world. Use these insights and checklists to audit and improve your site. Remember, every millisecond counts, and every optimization can make a huge difference.

Recap Checklists:

  1. Improving Core Web Vitals
    • LCP: Optimize the server, load critical resources.
    • INP: Minimize JavaScript and optimize long tasks by splitting them.
    • CLS: Reserve space for images and iframes, load fonts asynchronously, set width and height attributes on images.
  2. Optimizing Responsive Images
    • Convert images to WebP or AVIF formats.
    • Use the srcset attribute for adaptive images.
    • Implement lazy-loading for off-screen images.
  3. Reducing Unused Resources
    • Audit and identify unused CSS and JS resources.
    • Conditionally load scripts and styles.
    • Minify and compress CSS and JS files.
  4. Using Content Delivery Networks (CDN)
    • Use CDNs to bring content closer to end-users.
    • Properly configure CDNs to maximize load time benefits.
  5. Advanced Techniques for Faster Pages
    • Cache static resources.
    • Preload critical resources.
    • Speculation Rules
  6. Continuous Monitoring
    • Use Synthetic Monitoring tools for repeatable and controlled tests.
    • Use RUM tools to analyze real user performance.

Optimize well and may the speed be with you! 🚀

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