Fix Guide

How to Fix a Slow Time to First Byte (TTFB)

Cut server response time so the browser starts rendering sooner. Aim for a TTFB under 800ms.

Hard Critical Impact 45 min

Why It Matters

TTFB is how long the server takes to send the first byte of HTML. A slow TTFB delays everything after it, including LCP. Aim for under 800ms. Common causes: no caching, slow database queries, no CDN, and distant hosting.

How to Fix

Cache the HTML

Serve cached/static HTML for anonymous traffic instead of rebuilding the page per request (full-page cache, ISR, or a reverse proxy like Varnish/Cloudflare).

Put a CDN in front

A CDN serves cached responses from an edge near the user, cutting network latency dramatically for a global audience.

Profile the slow path

If the page is dynamic, profile the backend — add indexes for slow queries, cache expensive calls, and upgrade undersized hosting.

Code Fix

http

Before (broken)

# Every request hits PHP/DB and rebuilds the page
Cache-Control: no-store

After (fixed)

# Cache anonymous HTML at the edge
Cache-Control: public, s-maxage=300, stale-while-revalidate=86400

Platform-Specific Instructions

WordPress

Enable a full-page cache (WP Rocket, LiteSpeed, or Cloudflare APO) and object caching with Redis. Avoid heavy page builders on high-traffic pages.

Next.js

Use static generation or ISR (revalidate) for pages that don't need per-request data, and cache fetch() calls.

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How to Fix a Slow Time to First Byte (TTFB) — Fix Guide | SlapMyWeb