A content delivery network is a set of servers around the world that keep copies of your site's files and hand them to visitors from the nearest location. For a site in London with visitors in Sydney, the difference is a 300 ms round trip versus a 20 ms one — on every image, script and stylesheet. Whether that matters for your site depends on where your visitors are and what your pages are made of.
How it works
You point the domain at the CDN instead of your server. When a visitor requests example.com/logo.png, the CDN node nearest them checks whether it has a copy. If so, it serves it — your server is never involved. If not, it fetches from your server once, stores it, and serves it to the next thousand visitors from cache.
Static files cache well: images, CSS, JavaScript, fonts, downloads. HTML pages can be cached too, if the page is the same for every visitor; logged-in pages and carts cannot.
What it speeds up
- Distance. Physics: light in fibre takes about 5 ms per 1,000 km, and a page load needs many round trips. Serving from 50 km away instead of 17,000 km removes most of the wait.
- Your server's load. If 80% of requests are static files served by the CDN, your server handles 20% of the traffic — which is why a small VPS behind a CDN survives a front-page-of-Reddit spike.
- TLS and HTTP/3. CDNs terminate TLS at the edge with modern protocols, and keep a warm connection to your origin.
- Compression and image optimisation. Most CDNs Brotli-compress text and can resize or convert images to WebP on the fly.
What it does not speed up
- Time to first byte for dynamic pages. A WooCommerce cart page is generated by PHP on your server for each visitor; the CDN passes the request through and adds a hop. If your server takes 800 ms to build a page, the CDN delivers it in 810 ms. The fix for that is caching and tuning on the server.
- A slow database or bloated theme. Same reason.
- Visitors who are already near your server. A UK site with UK visitors on a UK server gains little from geographic distribution — the CDN's other benefits (offloading, DDoS absorption) may still apply.
The DDoS side benefit
Because all traffic passes through the CDN's network, which is built to absorb terabits, a volumetric attack hits the CDN, not you. This alone is why many sites use one; see DDoS and Anti-DDoS protection.
Options
Cloudflare — the default choice. The free plan includes the CDN, DDoS protection, a basic WAF and DNS. Setup is changing nameservers; nothing on the server changes. The gotchas: set SSL mode to Full (strict) so traffic to your origin stays encrypted; your server's logs show Cloudflare's IPs unless you restore the visitor IP (a one-line Nginx config or the Plesk Cloudflare extension); and the free plan caches only static files by default — page caching for HTML needs a Cache Rule.
BunnyCDN — cheap, fast, pay per GB, no free tier. Good for sites that mainly need media delivery rather than a full proxy.
Amazon CloudFront, Fastly, Akamai — enterprise options with pricing and configuration to match.
Your host's CDN — some hosts bundle one; check whether it is a real global network or a marketing name for their own cache.
Does your site need one?
| Situation | CDN? |
|---|---|
| Visitors mostly in the same country as the server | Optional — for DDoS and offload only |
| International audience | Yes |
| Image-heavy pages, downloads, video | Yes |
| Traffic spikes (launches, press) | Yes |
| Site has been DDoS'd or is a likely target | Yes |
| Small local business site, UK visitors, UK server | No measurable gain |
| Slow because of PHP/database | No — fix the server first |
Setting expectations
Measure before and after with PageSpeed Insights from a location far from your server. A properly configured CDN typically cuts Largest Contentful Paint by 20–50% for distant visitors and by little for local ones. If the number does not move, the bottleneck is on the server.
VPSPioneer's platform sits in the UK with a network built for UK and European visitors, and we set up Cloudflare in front of any site on request — it is part of onboarding on a managed VPS where the audience is international.