CDN Latency Test
Test CDN performance and latency from multiple global locations.
CDN latency measures how quickly content is delivered from a Content Delivery Network edge server.
Lower latency means faster page loads and better user experience.
Note: Results are measured from our server location.
Is your CDN actually faster? How to know for certain
Enabling a CDN doesn't guarantee faster delivery. The speed gain depends on cache hit rate, origin pull latency, and geographic routing — all of which vary by provider and configuration.
A CDN speeds things up when it's serving cached content from a node close to the user. If your cache-control headers are misconfigured, every request goes back to origin — you pay CDN pricing and get no speed benefit. This latency test measures TTFB from our infrastructure, telling you the actual first-byte response time of your CDN edge node as seen from an external network. Run it before and after CDN configuration changes to measure real impact.
TTFB vs. response time: what CDN testing actually measures
TTFB is how long until the first byte arrives. Total response time includes downloading the full response body. For CDN testing, TTFB is the critical number.
CDN optimization targets TTFB because that's where the benefit shows. A CDN edge node serves a cached response without touching your origin server — so TTFB drops from 400ms (origin roundtrip) to 40ms (edge cache hit). Total response time still includes content download, which isn't directly affected by CDN placement. When evaluating CDN performance, focus on TTFB: if it's under 100ms, your edge cache is working. If it's above 300ms, you're likely pulling from origin on every request.
CloudFront, Cloudflare, Fastly — latency profiles differ by provider
Different CDN providers have different edge node coverage maps. The 'best' CDN for your audience depends on where your users are, not which provider has the most data centers.
Cloudflare has the largest network by node count and performs best for globally distributed audiences. CloudFront is optimal when your origin is on AWS and your audience is in AWS-served regions. Fastly is common for high-traffic media and streaming, with strong edge compute capabilities. Akamai dominates in enterprise and financial services with deep SLA guarantees. Our latency test gives you a data point for comparing CDN performance against your baseline — run it with and without CDN to see the actual delta.
Cache hit vs. origin pull: the latency you're actually paying for
A cache miss on a CDN is often slower than no CDN at all — the request travels to the edge node and then back to origin, adding an extra hop.
When a CDN doesn't have a cached version of your content, it makes a request to your origin server and adds its own processing time on top. A cache miss can add 50-150ms of overhead vs. going directly to origin. The key to CDN performance is maximizing cache hit rate: set appropriate Cache-Control headers (max-age, s-maxage), avoid cache-busting query strings, and use CDN-level cache rules for static assets. If your TTFB is unexpectedly high despite using a CDN, a low cache hit rate is the most common explanation.