Time to First Byte (TTFB)
A metric measuring the time from request start until the first byte of the response is received.
Quick Definition
A metric measuring the time from request start until the first byte of the response is received.
Full Explanation
Time to First Byte (TTFB) measures how long it takes from when a user's browser sends a request to when it receives the first byte of the response. TTFB includes DNS lookup, TCP connection, TLS negotiation, and server processing time. While not a Core Web Vital itself, TTFB directly impacts LCP - your LCP cannot be faster than your TTFB. Google recommends TTFB under 800ms, with under 200ms being ideal. To improve TTFB, use a CDN, implement server-side caching, optimize database queries, use a fast DNS provider, and consider static site generation. Geographic distance significantly affects TTFB due to network latency.
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