Website Testing
Website Latency: Measure Real Latency to Any Site
When you say a website 'feels slow', latency is usually the culprit, not bandwidth. The Website Latency tool measures real round-trip latency to any URL or hostname, breaking down DNS lookup, TCP handshake, and TLS handshake so you can see where the time goes.
What It Measures
This tool measures website latency in milliseconds across multiple stages: DNS resolution, TCP connection, TLS handshake, and time to first byte (TTFB). It identifies which stage contributes most to total latency for a given URL.
How It Works
- Resolves the hostname using your configured DNS resolver
- Opens a TCP connection to the resolved IP and measures handshake time
- Performs the TLS handshake (for HTTPS) and measures negotiation time
- Issues a HEAD request and records time to first byte
Why It Matters
A slow loading website might have a fast server, a fast CDN, and your fast connection, but be hampered by DNS that takes 200ms or a TLS handshake that requires 4 round trips. Understanding which stage is slow tells you whether to switch DNS resolver, file a CDN routing complaint, or just accept the path is long.
Understanding Your Results
DNS lookup under 30ms is good. TCP handshake under 50ms to nearby servers, under 200ms to far servers. TLS handshake under 100ms with modern TLS 1.3, longer with TLS 1.2. Total time to first byte under 300ms feels snappy; over 1 second feels slow. CDN backed sites should consistently hit nearby PoPs with TTFB under 100ms.
Frequently Asked Questions
What slows down website latency the most?
Geographic distance from the server is the biggest factor on uncached content. For CDN backed sites, distance to the PoP matters most. DNS lookup time can add 50 to 200ms if your resolver is slow. TLS handshakes with old TLS 1.2 add 2 round trips. Servers without HTTP/2 or HTTP/3 lose multiplexing benefits and feel slower for multi resource pages.
How is this different from a browser DevTools timing?
Browser DevTools measure latency from your specific browser context with its caches, extensions, and possibly other tabs competing. The Website Latency tool measures clean latency from a single probe with no caching or interference, giving you a baseline measurement that's easier to compare across sites.
Why is DNS lookup so slow on my connection?
Slow DNS usually means your default resolver (often your ISP) is far away or under provisioned. Switching to Cloudflare (1.1.1.1) or Google (8.8.8.8) often cuts DNS lookup time by 50 to 200ms per request. Use the DNS Speed Test to compare resolvers for your specific location.
What is TTFB?
TTFB (Time to First Byte) is the time from issuing the HTTP request to receiving the first byte of response. It includes DNS, TCP, TLS, and the server processing time. A high TTFB on a static page suggests slow server side processing or distant origin. On dynamic pages, high TTFB can indicate database queries or backend latency.
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