Time To First Byte (TTFB)
A foundational web performance metric measuring the time from when a user makes a request to when their browser receives the very first byte of the HTML response. It is a fundamental measure of server and network responsiveness and is influenced by redirect time, DNS lookup, connection setup (including the TLS handshake), and the server's backend processing time. A slow TTFB creates a bottleneck for every subsequent metric, delaying both FCP and LCP.
Related web performance terms
- Tag Manager
A tag manager (like Google Tag Manager) is a system that allows marketing and business teams to add and manage third-party marketing tags (snippets of code for analytics, advertising, etc.) on a we…
- Third-Party Script/Tool
A third-party script or tool is any piece of code, functionality, or service that is provided by an external vendor and integrated into a website.
- Throttling (CPU & Network)
Throttling is a technique used in Lab Data tools (like Lighthouse) to simulate how a website would perform on slower devices or less reliable network connections.
- Time to Interactive (TTI)
Time to Interactive is a performance metric that measures the time it takes for a page to become fully and reliably responsive to user input.