What is TTFB?

TTFB (Time to First Byte) is the time elapsed between a browser sending an HTTP request and receiving the first byte of the server's response. A TTFB under 200ms is considered excellent; above 600ms indicates a server-side performance problem.

What is TTFB (Time to First Byte)?

Time to First Byte (TTFB) is a web performance metric that measures the duration from when a browser makes an HTTP request to when it receives the first byte of data from the server. It is one of the earliest signals of your server's responsiveness and a key component of Core Web Vitals measurements.

What TTFB Measures

TTFB encompasses three phases:

  1. DNS lookup time — Resolving your domain name to an IP address.
  2. TCP connection time — Establishing the connection between browser and server.
  3. Server processing time — The time the server spends generating the response (database queries, PHP execution, caching).

Of these, server processing time is the most controllable and has the biggest impact on TTFB for dynamic sites like WordPress.

What Is a Good TTFB?

  • Under 200ms — Excellent. Google considers this the target range for Core Web Vitals.
  • 200–600ms — Acceptable for many sites, but room for improvement.
  • Above 600ms — Poor. Indicates server-side bottlenecks that need attention.

What Affects TTFB?

  • Hosting quality — The server's hardware, load, and configuration have the biggest impact.
  • Server location — Physical distance from visitor to server adds unavoidable latency.
  • Database performance — Slow or unindexed queries are a common culprit on WordPress sites.
  • Caching — A full-page cache (like LiteSpeed Cache or WP Rocket) can reduce TTFB from 800ms to under 50ms by bypassing PHP and database entirely.
  • PHP version — PHP 8.x is significantly faster than PHP 7.x.

How to Measure TTFB

Use tools like GTmetrix, WebPageTest, Pingdom, or Chrome DevTools (Network tab → first HTML document → TTFB row). For the most accurate results, test from a server location close to your actual audience.