The 100 on Lighthouse
Users leave sites that take longer than 3 seconds to load. Performance is directly correlated with conversion rates.
Core Web Vitals
Focus on LCP (Largest Contentful Paint), FID (First Input Delay), and CLS (Cumulative Layout Shift). These are Google's primary metrics for ranking speed.
Image Optimization
Use WebP or AVIF formats. In Next.js, always use the <Image /> component to handle automatic resizing and lazy loading.
Code Splitting
Don't send the entire app to the user at once. Use dynamic imports to only load components when they are needed.
Measure, optimize, repeat. Tools like PageSpeed Insights and Sentry are your best friends.