Web Performance Optimization: Complete Guide

Your site's performance directly impacts user experience, SEO, and conversions. Every extra second of loading time can mean lost users.

Why Does Performance Matter?

• 53% of mobile users abandon sites that take longer than 3s to load
• Google uses speed as a ranking factor
• Fast sites have higher conversion rates

Core Web Vitals

LCP (Largest Contentful Paint) Time to load the largest visible element. Target: < 2.5s

**How to optimize:** - Optimize images (WebP, lazy loading) - Prioritize critical resources - Use a CDN

FID (First Input Delay) Time until the first interaction. Target: < 100ms

**How to optimize:** - Minimize JavaScript - Use code splitting - Avoid long tasks

CLS (Cumulative Layout Shift) Visual stability. Target: < 0.1

**How to optimize:** - Define dimensions for images - Reserve space for ads - Avoid dynamic content insertion

Image Optimization

Modern Formatos - WebP for modern browsers - AVIF for maximum compression - Fallback to JPEG/PNG

Lazy Loading Load images on demand.

Responsive Srcset Serve right-sized images for each device.

JavaScript Optimization

Code Splitting Load only the code needed for each page.

Tree Shaking Remove unused code in the build.

Defer and Async - defer: Loads in parallel, executes after parsing - async: Loads and executes in parallel

Caching

Browser Caching Configure appropriate Cache-Control headers.

Service Workers Implement offline caching for apps.

CDN Distribute assets globally.

Analysis Tools

• Lighthouse
• PageSpeed Insights
• WebPageTest
• Chrome DevTools

Conclusion

Performance is not a luxury; it is a necessity. At Johnny Software Development, performance optimization is part of our standard development process.