What is Page Speed? Complete Guide with Examples
Page speed measures how quickly a web page loads and becomes interactive for users. It encompasses multiple metrics: Time to First Byte (TTFB), First Contentful Paint (FCP), Largest Contentful Paint (LCP), Cumulative Layout Shift (CLS), and Interaction to Next Paint (INP). Page speed is a confirmed Google ranking factor and directly impacts user experience, bounce rates, and conversion rates.
How Does Page Speed Work?
Page loading involves multiple steps: DNS resolution, TCP connection, TLS handshake, HTTP request/response, HTML parsing, CSS/JS download and execution, rendering, and layout. Each step adds latency. Speed optimization targets these bottlenecks: CDNs reduce network latency, compression reduces transfer size, caching avoids redundant downloads, code splitting reduces JavaScript execution time, and image optimization reduces the largest content element's load time. Core Web Vitals (LCP < 2.5s, INP < 200ms, CLS < 0.1) are the key metrics Google uses for ranking.
Key Features
- Core Web Vitals measurement: LCP (loading), INP (interactivity), CLS (visual stability)
- Waterfall analysis showing resource loading sequence and timing bottlenecks
- Performance scoring from 0-100 based on lab and field data metrics
- Specific optimization recommendations with estimated impact for each fix
- Mobile and desktop separate scoring reflecting different network and device constraints
Common Use Cases
SEO Ranking Improvement
Google uses Core Web Vitals as a ranking signal. Sites with good page speed scores have a ranking advantage over slower competitors, especially on mobile where speed differences are more pronounced.
Conversion Rate Optimization
Amazon found that every 100ms of latency costs 1% in sales. E-commerce sites optimize page speed to reduce cart abandonment and improve conversion rates across the purchasing funnel.
User Experience Enhancement
Fast pages provide better user experiences. Users expect pages to load in under 3 seconds on mobile. Slow pages increase bounce rates — 53% of mobile users leave sites that take over 3 seconds to load.