“Zero TTFB” usually means an idealized target or a value shown by a measurement tool—not that a normal browser navigation took no time. Static and pre-rendered HTML can skip request-time page generation, and an edge-cache hit can sometimes avoid a trip to the origin. Neither removes all network and browser work, and a fast first byte does not guarantee that visitors see useful content quickly.
What does zero TTFB mean?
Time to First Byte (TTFB) measures the interval from the start of a request to the start of the response. For a page navigation, the browser’s Navigation Timing API commonly uses responseStart. MDN describes TTFB as “the time it takes between the start of the request and the start of the response, in milliseconds.” MDN Web Docs: Time to First Byte.
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That interval is not just the time a server spends producing HTML. It can include redirects, service-worker startup, DNS lookup, connection setup—including TCP and TLS for HTTPS—and the request’s journey to the first response byte. With HTTP 103 Early Hints, responseStart may reflect the interim response; where supported, finalResponseHeadersStart marks the beginning of the final response. MDN: PerformanceNavigationTiming.
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Can a static website have zero TTFB?
Static generation or pre-rendering makes the HTML available before a visitor requests it. The server therefore may not need to run application code or query a database to build that page for every request. This can shorten one part of the response path, but does not erase DNS, connection, request, or network time.
A CDN edge cache can further reduce the path for an eligible request: when cached HTML is served from an edge location, the request may not need to reach the origin. Whether that happens depends on cache rules and request state. Personalized or logged-in pages commonly need different handling from public pages, and cached content may need purging when it changes. Cloudflare: Introducing HTML Early Hints.
“Static” does not guarantee identical delivery for every route or visitor. Some pages may be generated dynamically, some requests may miss the cache, and authentication or personalization can change whether a response is cacheable. The accurate claim is that pre-rendering and edge caching can remove work or distance from the path under particular conditions—not that every visitor receives a zero-time response.
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Why does my TTFB show 0 ms?
First identify what kind of timing entry the tool measured. A zero in a subresource’s Resource Timing entry is not necessarily a zero-duration page navigation. For resource entries, responseStart can be zero when the resource came from cache or when cross-origin timing details are unavailable because the response lacks a Timing-Allow-Origin header. web.dev: Time to First Byte (TTFB).
For a navigation measurement, inspect the navigation entry rather than a CSS, script, image, or other subresource entry. In the browser console, for example:
performance.getEntriesByType('navigation')[0]?.responseStartThat value is in milliseconds. Also check the measurement tool’s definition, whether the request was a navigation, whether the response was cached, and whether the result is a rounded or unavailable value. A displayed zero should not be described as proof that the full navigation had no elapsed time.
Does pre-rendering eliminate TTFB?
No. Pre-rendering removes or reduces the need to generate HTML at request time; it does not eliminate the request’s network phases. A cached response can avoid contacting the origin, but the browser still has to make a request and receive a response. The size of any improvement depends on the route, cache state, geography, connection, and delivery setup.
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One free scan finds every outdated or missing driver and matches the right update for your exact hardware.Free scan · exact hardware matchFor a meaningful comparison, hold the request conditions steady and compare the actual delivery paths:
- Build path: request-time rendering versus prebuilt or pre-rendered HTML.
- Cache state: a cold request or cache miss versus a warm hit; note whether a browser cache or CDN was involved.
- Request conditions: use the same URL, test location, browser, connection, redirects, and authentication or personalization state.
- Delivery route: establish whether the request passed through a CDN and, where available, record the cache hit or miss.
Cloudflare’s test guidance recommends comparing its proxy paused and enabled and cautions that the first test may be uncached. It also says TTFB is not its most important measure of page-load speed. Cloudflare Speed Observatory.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Does a near-zero TTFB mean the page is fast?
Not by itself. TTFB ends when the first response byte arrives; the browser may still need to download HTML, CSS, JavaScript, fonts, and images, then parse, execute, and render them. A page can return a first byte quickly yet take longer to show its main content or become usable.
Interpret TTFB alongside user-facing measures such as First Contentful Paint (FCP) and Largest Contentful Paint (LCP), and consider interactivity and visual stability where relevant. A client-rendered application may receive an early response but still need substantial JavaScript work before content appears. Conversely, a server-rendered page with a higher TTFB may deliver useful content with less client-side work. The right comparison is the visitor’s experience, not the first-byte number in isolation.
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How should you measure TTFB?
Use a navigation measurement when the question is how quickly a page navigation begins receiving its response. In browser code, read the navigation entry’s responseStart; alternatively, use the web-vitals library’s onTTFB helper. Keep that result separate from Resource Timing values for subresources, which have distinct cache and cross-origin timing caveats. MDN: PerformanceNavigationTiming; web.dev: Time to First Byte (TTFB).
For real-user data, web.dev identifies the Chrome User Experience Report (CrUX) and the web-vitals library as field options. Browser developer tools and WebPageTest are lab options for controlled tests. Field data reflects visitors’ varied devices and networks; lab tests help isolate a delivery change under specified conditions. Compare TTFB with FCP or LCP so a quicker response is not mistaken for faster visible content.
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