TTFB (Time to First Byte)

It is the earliest measurable point in page loading - before a single image or line of CSS has had time to download. High TTFB (above ~800 ms) means the server or database is slow before the browser starts rendering anything, and everything that follows it (LCP, interactivity) builds on that foundation.

Typical causes include a slow database without indexes, a server without caching, and hosting geographically distant from the target audience. The solution is infrastructural, not cosmetic: statically generate pages where the content allows it (no database query for every request), deploy at the edge closer to the user, and cache at the CDN level.

Deployment through Vercel handles the last point automatically - an edge network close to the user without manual configuration. The rest (database queries, caching) is an architectural decision made during the build, not afterward.