Matan · SEO · Performance

TTFB

Time to first byte is the wait before any HTML arrives — usually origin or TLS overhead.

Pass condition in our engine: TTFB is under 200ms (info/warning up to 500ms).

1. Problem description

A 600ms TTFB means the user stares at a blank screen before LCP can even start. Google’s guidance still treats TTFB as a diagnostic, not a Core Web Vital, but it strongly predicts LCP.

2. Most common causes

  • Cold starts on serverless functions.
  • Synchronous API calls in the HTML renderer.
  • TLS handshake to a distant origin without a CDN.

3. How to fix it

  1. Put a CDN in front and cache anonymously cacheable pages.
  2. Pre-render or ISR static pages.
  3. Move slow data fetching off the critical HTML path.

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