Technical SEO
Time to First Byte (TTFB)
Last updated
What is Time to First Byte (TTFB)?
Time to First Byte (TTFB) measures the duration from when a browser sends an HTTP request to when it receives the first byte of the server's response. It reflects the combined latency of network conditions, server processing time, and the time it takes for the server to begin sending data. Google considers a TTFB under 800 milliseconds to be "Good." High TTFB is often the root cause of poor LCP scores.
TTFB is influenced by server hardware and configuration, application code efficiency (including database query time), geographic distance between user and server, and CDN effectiveness. A slow TTFB is a foundational performance problem: even if all other page assets are optimized, a slow initial server response delays everything else. Caching, CDN edge delivery, and server-side optimization are the primary remedies.
Why it matters for SEO
TTFB is the foundational performance metric that sets the ceiling for all subsequent page loading times. A high TTFB delays LCP and all other rendering milestones, making it a critical factor to address before optimizing other performance aspects.
Example
A WordPress site on cheap shared hosting takes over a second before the server sends the first byte of HTML, because every page view runs dozens of database queries. Adding full-page caching and serving cached pages through a CDN means most visitors get the HTML from a nearby edge server within a fraction of that time, and everything else on the page starts loading sooner.
Free tools for Time to First Byte (TTFB)
Go further with Time to First Byte (TTFB)
Put the theory to work
LazySEO researches keywords, writes SEO articles and publishes them to your site on a schedule.