What Is TTFB (Time to First Byte)?

Time to First Byte (TTFB) is the interval between requesting a page and receiving the first byte of the response — the server-and-network half of page speed, before the browser renders anything. It is not a Core Web Vital itself, but it is the floor under LCP: nothing paints faster than the HTML arrives.

What happens inside a TTFB

1. DNS lookup → TCP handshake → TLS negotiation (the connection tax, ~100–300 ms cold).
2. Any redirects — each one repeats the whole dance; redirect chains are TTFB poison.
3. Server think-time: database queries, template rendering, cold starts.
4. First byte travels back.

Healthy ranges

The improvement ladder, by leverage

1. Cache at the edge: static and prerendered pages from a CDN make geography irrelevant — the single biggest lever, and why static-first frameworks (Hugo, static Next.js exports) post 50 ms numbers.
2. Kill redirect chains: http→https→www→trailing-slash is three round trips before byte one; collapse to a single hop.
3. Fix the slow queries: server think-time is application work — profile the endpoints your top pages hit.
4. Watch it per page, from the field: your office fiber hides what your second-biggest market suffers. Per-visit timing data (field monitoring) segments TTFB by geography and page, which is where the 'CDN misses in Australia' class of problem becomes visible.

Rule of thumb: spend no effort on render optimization until TTFB is under control — you cannot polish bytes that have not arrived.