SEO Term Definition
Site Speed
Site speed refers to how quickly web pages load for users. It is a confirmed Google ranking factor for both desktop and mobile search, and directly impacts user experience, bounce rates, and conversion rates.
Reviewed by Alexander Yarovenko · Updated: 2026-07-03
What is Site Speed?
Site speed refers to how quickly a website's pages load and become interactive for users. Google confirmed page speed as a ranking factor for desktop search in 2010 and for mobile search in 2018. It also directly impacts user behaviour: Amazon found a 1-second delay reduces conversions by 7%; Google found 53% of mobile users abandon a page that takes more than 3 seconds to load.
Key Speed Metrics
| Metric | What it measures | Good threshold |
|---|---|---|
| LCP (Largest Contentful Paint) | When the main content loads | Under 2.5 seconds |
| FID / INP (Interaction to Next Paint) | Responsiveness to first interaction | Under 200ms |
| CLS (Cumulative Layout Shift) | Visual stability | Under 0.1 |
| TTFB (Time to First Byte) | Server response time | Under 200ms |
| FCP (First Contentful Paint) | When something first appears | Under 1.8 seconds |
How to Improve Site Speed
- Use a fast host / CDN — server location and quality directly affects TTFB
- Compress images — convert to WebP/AVIF; resize to actual display size; use lazy loading
- Minify CSS, JS, HTML — remove whitespace, comments, and unused code
- Eliminate render-blocking resources — defer non-critical JS; inline critical CSS
- Enable browser caching — returning visitors load cached assets
- Use lazy loading — off-screen images load only when user scrolls to them
- Reduce third-party scripts — analytics, chat widgets, ad tags can significantly slow pages
Tools for Measuring Site Speed
- Google PageSpeed Insights — free; lab and field data; actionable recommendations
- Google Search Console (Core Web Vitals report) — real-user data at scale
- WebPageTest.org — detailed waterfall charts; test from different locations
- GTmetrix — combined PageSpeed + YSlow scores; historical tracking