Bundle Analysis & Performance Impact

Detailed comparison of bundle sizes and performance metrics between regular imports and dynamic imports.

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❌ Regular Imports

Main Bundle (with all imports)

~400KB

Includes Chart.js, Lodash, date-fns, and all components

Chart.js

~200KB

Complete charting library loaded upfront

Lodash

~70KB

Utility library loaded immediately

date-fns

~20KB

Date formatting library in main bundle

Total Initial Bundle:~400KB

✅ Dynamic Imports

Main Bundle (minimal)

~100KB

Only core app code and React

Chart Component Chunk

~200KB

Loaded only when chart is requested

Table Component Chunk

~90KB

Loaded only when table is requested

Calculator Component Chunk

~70KB

Loaded only when calculator is requested

Initial Bundle:~100KB

75% smaller initial bundle!

⚡ Performance Impact

Core Web VitalRegular ImportsDynamic ImportsImprovement
First Contentful Paint (FCP)2.1s1.4s33% faster
Largest Contentful Paint (LCP)2.8s1.9s32% faster
Time to Interactive (TTI)3.5s2.2s37% faster
Total Blocking Time (TBT)400ms200ms50% reduction

🌍 Real-World Benefits

User Experience

  • Faster initial page loads improve user perception
  • Reduced bounce rates on slow connections
  • Better experience on mobile devices
  • Components load only when needed

Business Impact

  • Better SEO rankings (Core Web Vitals)
  • Reduced bandwidth costs
  • Higher conversion rates
  • Better accessibility compliance

🛠️ Implementation Best Practices

When to Use Dynamic Imports

  • • Large third-party libraries (Chart.js, Monaco Editor, etc.)
  • • Components used conditionally or in modals
  • • Route-specific functionality
  • • Feature flags or A/B test components
  • • Admin or power-user features

Code Example

// ❌ Regular import - included in main bundle
import HeavyComponent from './HeavyComponent';

// ✅ Dynamic import - code-split into separate chunk
const DynamicHeavyComponent = dynamic(
  () => import('./HeavyComponent'),
  {
    loading: () => <LoadingSpinner />,
    ssr: false // Disable SSR if not needed
  }
);

Tips for Success

  • • Use meaningful loading states to improve perceived performance
  • • Consider preloading critical dynamic components on hover/focus
  • • Analyze your bundle with @next/bundle-analyzer
  • • Group related functionality into single dynamic imports
  • • Monitor Core Web Vitals in production