TTFB (Time to First Byte) measures the time elapsed from the moment a user requests a page to the moment the first byte from the server reaches the browser. It is a key indicator of server response speed and overall infrastructure health.
Target values:
- Good: under 800 ms
- Needs improvement: 800 ms – 1800 ms
- Poor: over 1800 ms
Factors that affect TTFB:
- Server location and geographic distance
- Server processing time (PHP/application performance)
- Database query speed
- CDN usage
- SSL handshake time
High TTFB directly worsens all of the page’s remaining metrics (LCP, FCP), because the page cannot do anything until the first byte arrives from the server.
Tip: To reduce TTFB, use a CDN, implement server-side caching, and optimize database queries. For static pages, implementing full-page caching is the fastest solution.