TTFB (Time To First Byte)
Time To First Byte (TTFB) is the time between making a request and receiving the first byte of the response.
TTFB captures server-side latency: DNS resolution, connection setup, and how long the server takes to start sending a response. A high TTFB points at backend or network problems rather than front-end rendering.
It is a component of overall response time and a useful diagnostic when a site feels slow before anything even appears on screen.
Related terms
Response TimeResponse time is how long a service takes to respond to a request, usually measured in milliseconds.Real User Monitoring (RUM)Real User Monitoring (RUM) measures performance and errors from the browsers of your actual visitors, capturing what real people experience.DNS (Domain Name System)The Domain Name System (DNS) translates human-readable domain names like example.com into the IP addresses computers use to connect.
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