What is Time to First Byte (TTFB)?
Time to First Byte (TTFB) measures the time from when a browser makes an HTTP request to when it receives the first byte of the response from the server. It encompasses DNS resolution, TCP connection, TLS handshake, and the time the server takes to process the request and begin sending a response. TTFB is the foundational metric — every other performance metric is delayed by TTFB.
What TTFB Measures
TTFB captures total server-side and network latency before any content can be delivered to the browser. A slow TTFB delays FCP, LCP, and every other user-facing metric because the browser cannot render anything until it has received at least some HTML. TTFB above 800ms is flagged by Lighthouse as "Reduce initial server response time."
What is a Good TTFB Score?
What Causes Poor TTFB Scores?
- ✗No page caching — the server generates each page dynamically on every request (common cause on WordPress without caching plugins)
- ✗Slow database queries — server-side code waiting on slow database responses before sending HTML
- ✗No CDN — servers geographically far from users add significant network round-trip time
- ✗Shared hosting with resource constraints — CPU and memory limits causing slow response times under load
- ✗Overloaded origin server — insufficient server capacity for the current traffic level
- ✗Unnecessary server-side redirects — each redirect adds a full round trip before the final content loads
How to Fix TTFB
- ✓Implement full-page caching — WP Rocket or W3 Total Cache for WordPress; built-in for Next.js/Vercel/Netlify
- ✓Deploy a CDN (Cloudflare, Fastly, or similar) to serve cached pages from edge nodes close to users
- ✓Optimize database queries — add indexes, paginate large result sets, use a query cache like Redis
- ✓Eliminate unnecessary redirects — internal links should point directly to the canonical URL
- ✓Use a faster hosting provider or scale up server resources if under load
- ✓Enable keep-alive connections and HTTP/2 to reuse TCP connections
Check Your TTFB Score
Run a free Lighthouse audit at speedexporter.com — the "Server response times (TTFB)" audit shows your exact TTFB measurement and whether it needs improvement.
Run a free Lighthouse audit →Frequently Asked Questions
What is a good TTFB?
Google's guidance is that TTFB should be under 800ms. Under 200ms is considered excellent. Most well-configured CDN-served pages achieve 50-150ms TTFB for users in the same region as the CDN edge.
Does TTFB affect Core Web Vitals?
TTFB is not itself a Core Web Vital, but it directly delays LCP and FCP, which are Core Web Vitals. Every millisecond of TTFB is added to every downstream metric. Fixing high TTFB is often the single highest-impact optimization.
What is the difference between TTFB and FCP?
TTFB is when the server starts responding. FCP is when the browser renders the first visible content. TTFB is always ≤ FCP because the browser cannot render anything before it has started receiving HTML.
How do I fix TTFB on WordPress?
The fastest fixes for WordPress TTFB are: (1) install WP Rocket or W3 Total Cache for page caching, (2) use Cloudflare or a similar CDN, (3) switch to a faster managed WordPress host, and (4) enable Redis or Memcached for database query caching.