TTFB (Time to First Byte)
TTFB measures the time from when a browser requests a page to when it receives the first byte of data from the server, serving as a key indicator of server responsiveness.
Time to First Byte (TTFB) is a performance metric that measures the duration between a user's browser sending a request and receiving the very first byte of the server's response. It captures three phases: the time to send the request, the time the server takes to process it, and the time for the first byte to travel back. A good TTFB is under 200 milliseconds.
Google considers TTFB when evaluating page experience, though it's not one of the Core Web Vitals. Several factors affect TTFB. Server processing time depends on how long it takes to run database queries, execute server-side code, and generate the response.
In practice
- A WordPress site with a TTFB of 1.8 seconds implemented server-side caching and reduced it to 150ms, cutting total page load time by more than half
- An e-commerce platform discovered their TTFB was 900ms due to slow database queries; adding database indexes and query caching brought it down to 120ms
- A media site moved their origin server from a single US location to a CDN with edge caching, reducing TTFB for European users from 800ms to 80ms
- A SaaS dashboard reduced their TTFB from 1.2 seconds to 200ms by pre-computing frequently accessed data and caching the results
Not sure how this applies to you?
A senior engineer walks your site, your search presence and the way enquiries reach you, then writes down the three things worth fixing first. You keep the document either way.