Learn Web Performance
Everything you need to know about making websites fast
Why Performance Matters
of mobile users leave if a page takes over 3 seconds to load
increase in conversions for every second of improvement
Every 100ms of delay reduces conversion rates
Core Web Vitals Explained
Largest Contentful Paint (LCP)
Loading performance
LCP measures how long it takes for the main content to load. Good LCP means users see your content quickly and don't feel like they're waiting.
How to improve:
- Optimize and compress images
- Use a CDN like fast.site for faster delivery
- Preload important resources
Interaction to Next Paint (INP)
Interactivity
INP measures how responsive your page is when users interact with it. Good INP means buttons and links respond immediately.
How to improve:
- Break up long JavaScript tasks
- Minimize main thread work
- Use web workers for heavy processing
Cumulative Layout Shift (CLS)
Visual stability
CLS measures how much the page layout shifts while loading. Good CLS means things don't jump around unexpectedly.
How to improve:
- Always include size attributes on images
- Reserve space for ads and embeds
- Avoid inserting content above existing content
External Resources
web.dev - Web Vitals
Google's official guide to Core Web Vitals and web performance best practices.
Google Web Performance
Comprehensive resources from Google about website speed and optimization.
Lighthouse Documentation
Learn about the testing tool that powers PageSpeed Insights.
Case Studies
Real examples of companies improving their web performance.
Put your knowledge to the test
Now that you understand the basics, analyze your site and see how it measures up.
Analyze Your Site