miji.beTTFB (Time to First Byte) measures the elapsed time from the moment a browser starts navigating to a page to the moment the very first byte of the server's response begins to arrive. It is the most fundamental indicator of server responsiveness and the starting point for all web performance analysis.
TTFB covers the time spent on redirects, service worker startup, DNS lookup, connection and TLS negotiation, and finally the request itself up to the point where the first byte of the response arrives. Server-side processing sits inside that last segment, so when TTFB is high it pays to separate slow server work from time spent waiting on name resolution and connection setup.
Google classifies TTFB as a supplementary Core Web Vitals metric. A good TTFB is 800 ms or less, the 800 ms to 1800 ms band needs improvement, and anything above 1800 ms counts as poor. For shortened URL redirects, where the server simply looks up a mapping and returns a 301/302, the target should be under 50 ms.
Optimization techniques for a URL shortening service include CDN deployment (serving responses from edge locations close to the user), in-memory caching with Redis (caching URL mappings for sub-millisecond lookups), database index tuning, and enabling HTTP/2 for connection multiplexing.
Measurement tools include the Waiting (TTFB) entry in the timing breakdown of the Chrome DevTools Network panel, Lighthouse performance audits, curl (curl -w '%{time_starttransfer}' URL), and WebPageTest. Separating server processing time from network transit time pinpoints the actual bottleneck.