Time to First Byte (TTFB) (Usability)

Code received in 0.8 seconds.

Impact

(ScanGov impact)

About

Time to First Byte (TTFB) measures the time it takes from when a browser requests a resource to when the first byte of data begins to load. It's an important metric for website performance, affecting how quickly a page appears. A good TTFB is under 0.8 seconds, and anything over 1.8 seconds needs improvement. TTFB is influenced by server responsiveness and connection setup time. Lowering it can improve overall user experience and speed.

Why it's important

Measures how quickly a server responds, impacting page load speed and user experience by reducing wait times.

User stories

As a user requesting a web page, I want the server to respond quickly so that the page starts loading without noticeable delay.

Error

(ScanGov messaging when a site fails a standard)

Server response took over 0.8 seconds.

Guidance

• Web Vitals / Core Web Vitals

Indicators

• Usability

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