Next.js 15 Performance Optimization: A Complete Guide

Performance is not just a technical metric—it's a business metric. Here's how to make your Next.js app faster.

Core Web Vitals Optimization

Largest Contentful Paint (LCP)

• Use next/image with proper sizing and priority loading
• Implement static generation where possible
• Use a CDN for asset delivery

First Input Delay (FID) / Interaction to Next Paint (INP)

• Minimize JavaScript bundle size
• Use dynamic imports for heavy components
• Defer non-critical third-party scripts

Cumulative Layout Shift (CLS)

• Always specify image dimensions
• Reserve space for dynamic content
• Avoid inserting content above existing content

Code Splitting Strategies

import dynamic from 'next/dynamic';

const HeavyComponent = dynamic(() => import('./HeavyComponent'), {
  loading: () => <Skeleton />,
  ssr: false,
});

Image Optimization

Next.js Image component automatically optimizes images. Always use it instead of raw <img> tags:

• Set priority for above-the-fold images
• Use placeholder="blur" for better perceived performance
• Choose appropriate formats (WebP, AVIF)

Caching Strategy

Leverage Next.js caching layers:

• Static pages: Generated at build time
• ISR: Revalidate on interval for dynamic content
• Edge caching: Deploy on Vercel for global CDN

Measure the change

Check Largest Contentful Paint, Interaction to Next Paint, and Cumulative Layout Shift after each change, and keep the work that improves them.

Need help optimizing your Next.js application? Contact NKDigitech.