JavaScript Bundle Size Exceeds Vercel Limit
Your Next.js application has excessive JavaScript bundle size, causing slow page loads, poor Core Web Vitals scores, and potential Vercel function timeout issues. Build analysis shows bloated chunks.
Bundle size grows from unused dependencies, large libraries, lack of code splitting, or importing entire libraries instead of specific utilities.
Error Messages You Might See
Common Causes
- Importing entire libraries (lodash, date-fns) instead of specific functions
- Heavy dependencies without tree-shaking: moment.js, jQuery, momentjs alternatives
- Dynamic imports not configured, causing all routes bundled together
- Node modules accidentally included in client bundle
- No lazy loading for heavy components (charts, editors, maps)
How to Fix It
Analyze bundle: Use npm run build then npx next/bundle-analyzer to see what's bloating bundle.
Replace heavy libs: Swap moment.js for date-fns or dayjs, lodash for lodash-es with tree-shaking.
Lazy load components: Use dynamic imports for heavy components:const Chart = dynamic(() => import('@/components/Chart'), { ssr: false })
Check imports: Replace import _ from 'lodash' with import pick from 'lodash/pick'
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Get HelpFrequently Asked Questions
How big should my JavaScript bundle be?
Aim for <100KB main bundle. First-party code usually <50KB, dependencies <50KB. Use bundle analyzer to identify large packages.
What's the fastest way to reduce bundle?
Replace moment.js (67KB) with date-fns (13KB). Remove unused dependencies. Lazy load below-fold components.
How do I enable tree-shaking?
Ensure package.json has 'sideEffects': false. Use ES modules for imports. Webpack automatically tree-shakes unused code.