Content delivery networks, which are systems of distributed servers that deliver web content and pages to users more quickly and efficiently, work by distributing your website's content across a global network of edge servers to route users to the closest edge server for faster load times. Optimizing your CDN’s performance is a great strategy for improving overall web performance and its associated benefits.
When an organization focuses on optimizing web and application performance across its portfolio, even the smallest improvements can yield a meaningful performance boost. If you’re at all concerned with improving your performance then you should consider evaluating your existing content delivery network (CDN) tooling and strategy.
The following provides some best practices for improving your CDN performance plus actionable guidance on how to begin assessing your existing CDN strategy.
What is the importance of optimizing CDN performance/ what are the benefits?
Optimizing CDN performance is essential for delivering fast, reliable, and scalable digital experiences. A well-optimized CDN reduces latency by serving content from edge locations closer to end users, resulting in faster page loads, smoother streaming, and improved application responsiveness. This not only enhances user satisfaction but also increases engagement, conversion rates, and customer retention.
Beyond speed, CDN optimization improves infrastructure efficiency by reducing strain on origin servers through intelligent caching and traffic distribution. It also strengthens availability and resilience during traffic spikes or cyberattacks, helping businesses maintain consistent uptime and performance globally. By leveraging features like compression, edge computing, protocol optimization, and real-time traffic management, organizations can lower bandwidth costs, improve security, and ensure high-performance delivery across web, mobile, and API-driven applications.
Put simply, optimizing CDN performance results in happy customers, and happy customers are great for business.
What steps can you take to improve CDN performance?
Simply implementing a CDN is not enough to achieve optimal performance. Organizations must actively optimize their CDN configuration and delivery strategies to reduce latency, improve scalability, and create a better user experience. Below are some best practices to improve your CDN’s performance.
Optimize caching
One of the most effective ways to improve CDN performance is by optimizing caching policies. Caching allows content to be stored on edge servers closer to users so that requests can be served without repeatedly contacting the origin server. When static assets like images, CSS files, JavaScript, fonts, and videos are cached properly, websites load significantly faster and place less strain on backend infrastructure.
Setting appropriate cache-control headers and using versioned file names can help ensure that users receive fresh content while still benefiting from long cache lifetimes. A strong caching strategy also improves scalability during periods of high traffic because fewer requests are routed back to the origin.
Reduce origin requests
Reducing unnecessary origin requests is another critical aspect of CDN optimization. Every time content cannot be served from cache, the CDN must retrieve it from the origin server, which introduces additional latency and increases infrastructure load.
Businesses can minimize these requests by improving cache hit ratios, eliminating unnecessary query strings, and avoiding cookies on static resources. In some cases, edge logic can be used to normalize requests so that similar requests map to the same cached object. This approach helps maximize cache efficiency and reduces response times for users. Implement compression
Compression also plays a major role in improving CDN performance. Large files take longer to transfer across networks, especially on slower or mobile connections. Enabling modern compression methods such as Brotli or Gzip significantly reduces the size of HTML, CSS, JavaScript, JSON, and SVG files before they are delivered to users.
Smaller payloads lead to faster downloads, reduced bandwidth consumption, and better overall application responsiveness. Compression is particularly valuable for improving performance on mobile devices where network conditions may be less reliable.
Practice image optimization
Image optimization is another important focus for performance improvement because images are often the largest assets on a webpage. Organizations can improve delivery speeds by using modern image formats like WebP or AVIF, which provide higher quality at smaller file sizes compared to traditional formats like JPEG or PNG.
Dynamic image resizing at the edge can also ensure that users receive images optimized for their specific device and screen size. In addition, techniques like ‘lazy loading’ help prioritize visible content and reduce unnecessary bandwidth usage by loading images only when users scroll to them.
You can read our full guide on image optimization for further details.
Use modern network protocols
Modern network protocols can further enhance CDN efficiency. HTTP/2 improves performance by allowing multiple requests to be sent over a single connection, reducing overhead and latency.
HTTP/3 goes even further by using the QUIC transport protocol to establish faster and more resilient connections, particularly on mobile networks or unstable connections. Enabling support for HTTP/2 and HTTP/3 allows websites and applications to deliver content more efficiently and improve responsiveness for users across different environments.
Optimize DNS
DNS optimization also contributes to better CDN performance. Before a user can connect to a CDN, their device must first resolve the CDN’s domain name through DNS. Slow DNS resolution increases the time required to establish a connection.
Using a high-performance DNS provider, minimizing CNAME chains, and enabling DNS prefetching can help reduce lookup times and accelerate the initial connection process. Although DNS improvements may seem small individually, they can have a noticeable impact on perceived performance at scale.
Get strong insights
Monitoring and analytics are essential for maintaining strong CDN performance over time. Organizations should regularly track metrics like cache hit ratio, Time to First Byte (TTFB), origin offload percentage, latency, and error rates.
These metrics help identify inefficiencies and reveal opportunities for optimization. Real User Monitoring (RUM), CDN dashboards, Lighthouse, and performance testing tools like WebPageTest can provide valuable insight into how users experience content delivery in real-world conditions.
Focus on security
Security optimization is another important factor because cyberattacks and malicious traffic can negatively impact CDN performance. Enabling features like DDoS protection, Web Application Firewalls (WAFs), rate limiting, and TLS 1.3 helps protect infrastructure while maintaining fast and reliable delivery for legitimate users.
By filtering harmful traffic at the edge, organizations can preserve bandwidth and reduce strain on origin.
Three ways a modern CDN helps you improve performance/ How Fastly can help
If you have implemented all of the practices above and still aren’t seeing the performance you’re looking for, or your current CDN can’t support the above best practices, switching to a modern CDN comes with built-in capabilities that ensure the best in CDN performance.
Advanced caching
Sure, all CDNs provide some level of caching capabilities - they help you to reduce latency by delivering content from a location closer to your user and improve load times. But does your CDN truly offer ‘advanced’ caching?
Modern CDNs offer a key capability that allows you to cache more; they can cache ‘dynamic’ or frequently changing content (think account info, location-specific products, changing inventory, new headlines). Traditional CDN customers suffer, as their traffic has to return all the way back to the origin, which results in slower response times, increased infrastructure expenses, and more associated costs for egress data for those numerous (unnecessary) responses.
Instead, modern CDNs make it possible for your company to serve truly dynamic content that changes with every request from the edge, rather than from origin. This gives you the ability to run your code closer to the end user, eliminating costly and time-consuming performance degradations.
Advanced Origin Offload
The CDN you choose should remove the ‘strain’ or ‘tax’ on your origin. By minimizing the requests and demand on your origin, you enhance the overall performance of your network, sites and apps, and can enjoy decreased costs and time constraints. Cache hit ratio gets a lot of attention, but it’s not the full story.
In this blog post, Fastly engineers describe that a better measure for evaluating total offload to a CDN is origin offload. This measure focuses on server efficiency, and the number of bytes served from cache vs. origin, rather than just the number of requests. An origin offload of 100% means all bytes were served from the CDN. So what can you do to increase origin offload? Here are two key strategies that can have a huge impact on origin offload, on your performance, and on your egress bills.
Origin shielding: Shielding can significantly lower the strain on your origin by drastically cutting both the number of requests and the amount of data served. It also speeds up cache miss responses, which even lowers latency for requests served from origin.
Request collapsing: When request collapsing is enabled, your CDN will combine multiple requests for the same ‘object’ into a single request back to the origin. Without request collapsing, if a piece of very popular content is updated at origin, you run the risk of creating a stampede of every POP on the network sending a request to your origin at once.
Real-time Insights and Configurability
It’s impossible to know how you’re doing at something if you can’t accurately measure it and act on data in real-time. If you don’t have total control over your CDN, you don’t have control over your performance.
A modern CDN allows complete developer control and configurability, which means quick content changes, fine-grained control of content caching, and developer efficiency. If you need to make changes, for any reason - be it something happening in the business, teams reacting to metrics, and so on - your teams need the control to make configuration changes immediately.
With the right CDN, there is no need for professional service engagements or reliance on technical teams elsewhere in the business to accomplish this. This all results in faster time-to-market and better performance.
If you want to dig even deeper into the above strategies, grab a copy of Need for Speed: Guide to Faster Site, App, and API Performance with Your CDN