---
type: Glossary Term
title: "Time to First Byte (TTFB)"
description: "The time between request and the first byte of response from the origin or CDN."
resource: "https://prerendering.com/glossary/ttfb"
tags: [metrics, glossary]
timestamp: 2026-05-11T00:00:00Z
---

# Time to First Byte (TTFB)

The time between request and the first byte of response from the origin or CDN.

TTFB is what the crawler waits for before any rendering can begin. Good < 800ms. SSG TTFB is whatever the CDN responds in (30-100ms). SSR TTFB depends on origin and data dependencies (200ms-1.5s). Slow TTFB tends to depress crawl rate over time as Google adapts to perceived origin load.

Also known as: TTFB.