Web performance encompasses all aspects of how quickly and smoothly a website loads and responds. It directly impacts user experience, conversions, and search rankings.
Why web performance matters
User experience
- Users expect pages to load in under 3 seconds
- Slow sites have higher bounce rates
- Fast sites see more engagement
Business impact
- Amazon: 1 second delay = 1% revenue loss
- Google: 0.5 second delay = 20% traffic drop
- Better conversions and retention
SEO
- Core Web Vitals are ranking signals
- Better crawl efficiency
- Improved user metrics
Measuring web performance
Core Web Vitals
- LCP, INP, CLS
Other key metrics
- TTFB, FCP, Speed Index, TTI, TBT
Tools
- Lighthouse, PageSpeed Insights, WebPageTest
- RUM tools like VitalSentinel
Performance optimization pillars
- Server: Fast TTFB, CDN, caching
- Network: Compression, HTTP/2, fewer requests
- Rendering: Critical CSS, defer JS
- Assets: Optimized images, fonts
- Code: Efficient JavaScript, no bloat
Related Terms
Core Web Vitals
A set of three metrics defined by Google that measure the loading performance, interactivity, and visual stability of a web page.
Lighthouse
An open-source automated tool by Google for auditing the quality of web pages, measuring performance, accessibility, SEO, and more.
Page Experience
A set of signals that Google uses to measure how users perceive the experience of interacting with a web page beyond its pure information value.
Real User Monitoring (RUM)
A type of performance monitoring that captures and analyzes data from actual user sessions visiting a website.