slideshare/VITEBESTPRACTICES.md

Vite Best Practices & Performance Guide

Based on Vite Performance Documentation

Core Performance Principle

"Reduce the amount of work for source files (JS/TS/CSS)" to maintain performance as projects grow.

Browser Setup

Development Environment

• Create a dev-only browser profile without extensions
• Use incognito mode for faster performance
• Don't disable browser cache while using dev tools (it significantly slows down requests and HMR)

Plugin Management

Best Practices

• Be cautious with community plugins - they may impact performance
• Dynamically import large dependencies instead of importing them statically
• Avoid long-running operations in plugin hooks
• Minimize file transformation time

Import and Resolve Optimization

File Extensions

• Be explicit with import paths - use import './Component.jsx' instead of import './Component'
• Narrow down resolve.extensions list - don't include unnecessary file types
• Use common extensions first: ['.js', '.ts', '.jsx', '.tsx']

Module Imports

• Avoid barrel files that re-export multiple modules from index files
• Import individual APIs directly instead of from index files
• Example: Use import { debounce } from 'lodash-es/debounce' instead of import { debounce } from 'lodash-es'

File Transformation

Warmup Strategy

• Use server.warmup for frequently used files
• Pre-transform commonly accessed modules during dev server startup

Native Tooling

• Use native tooling when possible for better performance
• Consider these alternatives:
  • Rolldown instead of Rollup
  • LightningCSS for CSS processing
  • @vitejs/plugin-react-swc for React projects

CSS and Styling

CSS Optimization

• Use CSS instead of preprocessors when possible (native CSS is faster)
• Import SVGs as strings/URLs rather than components when appropriate
• Minimize unnecessary transformations

Performance Profiling

Diagnostic Tools

• Use vite --profile to generate performance profiles
• Use vite --debug plugin-transform to inspect transformation times
• Use tools like speedscope to analyze bottlenecks

Monitoring

• Track build times and identify slow transformations
• Monitor bundle sizes and chunk splitting effectiveness
• Profile HMR performance during development

Import Strategies

Dynamic Imports

// Good: Dynamic import for large dependencies
const heavyLibrary = await import('heavy-library');

// Bad: Static import of large library
import heavyLibrary from 'heavy-library';

Explicit Extensions

// Good: Explicit file extension
import Component from './Component.jsx';

// Bad: Missing extension (requires resolution)
import Component from './Component';

Direct API Imports

// Good: Direct import
import { debounce } from 'lodash-es/debounce';

// Bad: Barrel import (imports entire library)
import { debounce } from 'lodash-es';

Configuration Recommendations

Resolve Extensions (in order of frequency)

export default {
  resolve: {
    extensions: ['.js', '.ts', '.jsx', '.tsx', '.json']
  }
}

Server Warmup

export default {
  server: {
    warmup: {
      clientFiles: ['./src/components/**/*.tsx', './src/utils/**/*.ts']
    }
  }
}

Development vs Production

Development Focus

• Fast HMR and dev server startup
• Minimal transformations
• Browser-friendly module resolution

Production Focus

• Optimized bundle sizes
• Tree shaking effectiveness
• Code splitting strategies

Key Takeaways

1. Minimize transformations - every transformation adds overhead
2. Be explicit - help Vite resolve files faster with explicit paths
3. Use native tools - they're typically faster than JavaScript alternatives
4. Profile regularly - identify and fix performance bottlenecks early
5. Optimize imports - direct imports are faster than barrel imports
6. Consider browser setup - development environment affects performance significantly