⚡ Frontend Performance in 2025: The Ultimate Checklist

Source: Dev.to

Core Metrics to Track

• LCP (Largest Contentful Paint) – main content load speed
• FID (First Input Delay) – responsiveness
• CLS (Cumulative Layout Shift) – visual stability
• TTI (Time to Interactive) – when the user can actually interact

Optimizing these improves perception and retention.

Bundle Optimization

• Split code into chunks using Vite, Webpack, or Rspack
• Use ESM + tree‑shaking to remove dead code
• Compress images & fonts with modern formats (AVIF, WebP)

Smaller bundles = faster download = happier users.

Server‑Side & Edge Rendering

React 18 + Next.js 13 lets you leverage:

• Streaming SSR for faster first paint
• Incremental static regeneration (ISR) for dynamic content
• Edge functions to reduce latency

This ensures content reaches users fast, regardless of location.

Lazy Loading & Suspense

• Lazy‑load non‑critical components
• Use Suspense + skeletons to maintain perceived speed
• Defer third‑party scripts and analytics

Perception is everything — users care more about what they see than what they download.

Caching & Prefetching

• Cache API responses at the edge
• Prefetch data on hover or anticipation events
• Leverage service workers for offline support

Good caching reduces unnecessary network requests and keeps the app snappy.

Monitoring & Continuous Improvement

• Lighthouse & Web Vitals for automated audits
• Real User Monitoring (RUM) tools like Vercel Analytics or LogRocket
• Set up performance budgets to prevent regressions

Monitoring ensures optimizations stick as your app grows.

Resources

• 📚 Web Vitals Docs
• 🧠 Next.js Performance Optimization
• 🛠️ Vite Official Docs
• 🖼️ Frontend That Converts — Full Article