Definition
Server Response Time, closely related to TTFB (Time to First Byte), measures how quickly a server processes a request and starts sending the response. Google recommends a server response time under 200ms. A slow response time impacts LCP (Largest Contentful Paint) and degrades user experience. Influencing factors include server power, backend code efficiency, database queries, server caching, geographic distance, and server load. Optimizations include application cache (Redis, Memcached), SQL query optimization, CDN, HTTP keep-alive, and choosing hosting suited to the load.
Key Points
- Google recommends server response time under 200ms
- Server cache (Redis, Varnish) is the most effective method to reduce TTFB
- Response time directly impacts LCP and Googlebot's crawl experience
Practical Examples
Response time optimization
A WordPress site with 1.5s response time implements Redis as object cache, optimizes SQL queries, and activates OPcache. Response time drops to 180ms.
Core Web Vitals impact
An e-commerce site reduces server response time from 800ms to 150ms by migrating to a dedicated SSD server. LCP improves proportionally, going from 3.2s to 2.1s.
Frequently Asked Questions
Use WebPageTest, GTmetrix, or Chrome DevTools (Network tab, TTFB column). Google PageSpeed Insights also indicates server response time. For continuous monitoring, set up regular checks with UptimeRobot or Pingdom.
TTFB includes DNS time + TCP/TLS connection + server response time. Server Response Time is the purely server component (request processing). A high TTFB may come from slow DNS, not necessarily the server.
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Last updated: 2026-02-07