TTFB: the silent tax on every Core Web Vital

TTFB: the silent tax on every Core Web Vital

TTFB — Time to First Byte — measures how long your server takes to send the very first piece of data after a request. It's not a Core Web Vital itself, but it sits underneath all of them.

Think of it like waiting for a kitchen to even start cooking. Every later step — LCP, your images, your scripts — can't begin until that first byte arrives.

A good TTFB is under 800 milliseconds. If yours is sluggish, fixing images won't help much.

1. Check TTFB in PageSpeed Insights' diagnostics or DevTools Network tab.
2. Common causes: slow hosting, no caching, heavy database queries.
3. The easiest win is adding a CDN — a content delivery network — to serve cached pages from nearby.

Try this: test your page from a far-away location. A big TTFB jump means your server's distance is hurting real visitors.