slideshare/VITE_PERFORMANCE.md

# Vite Performance Standards

## Missing Configuration
The current `vite.config.ts` is missing critical performance optimizations.

## Required Vite Configuration Updates

### 1. Resolve Extensions (CRITICAL)
```typescript
// ADD to vite.config.ts
export default defineConfig({
  resolve: {
    extensions: ['.js', '.ts', '.jsx', '.tsx', '.json']
  }
});
```
**Impact**: Faster module resolution, explicit extension requirements

### 2. Server Warmup (HIGH IMPACT)
```typescript
// ADD to vite.config.ts
export default defineConfig({
  server: {
    warmup: {
      clientFiles: [
        './src/components/**/*.tsx',
        './src/utils/**/*.ts', 
        './src/types/**/*.ts',
        './src/themes/**/*.ts'
      ]
    }
  }
});
```
**Impact**: Faster initial load times, better dev experience

### 3. Build Optimizations
```typescript
// ADD to vite.config.ts
export default defineConfig({
  build: {
    rollupOptions: {
      output: {
        manualChunks: {
          vendor: ['react', 'react-dom'],
          router: ['react-router-dom'],
          themes: ['./src/utils/themeLoader', './src/utils/cssParser']
        }
      }
    }
  }
});
```
**Impact**: Better code splitting, improved cache utilization

### 4. Dependency Pre-bundling
```typescript
// ADD to vite.config.ts  
export default defineConfig({
  optimizeDeps: {
    include: ['react', 'react-dom', 'react-router-dom'],
    exclude: ['@vite/client', '@vite/env']
  }
});
```
**Impact**: Faster cold starts, consistent dependency handling

## Current Performance Issues

### 1. Barrel File Usage
**Problem**: Two barrel files present
- `src/components/themes/index.ts` 
- `src/themes/index.ts`

**Impact**: Prevents tree-shaking, slower builds
**Solution**: Remove barrel files, use direct imports

### 2. Missing File Extensions
**Problem**: Import statements lack explicit extensions
```typescript
// ❌ CURRENT
import App from './App.tsx'
import { getThemes } from '../../themes'

// ✅ SHOULD BE  
import App from './App.tsx'
import { getThemes } from '../../themes/index.ts'
```

### 3. No Warmup Configuration
**Problem**: Cold start performance is suboptimal
**Solution**: Configure server warmup for frequently accessed files

## Implementation Priority

### IMMEDIATE (Critical Performance Impact)
1. **Remove barrel file imports** - Replace with direct imports
2. **Add resolve extensions** - Configure explicit extension handling  
3. **Configure server warmup** - Improve dev server startup

### SHORT TERM (Build Performance)
1. **Add manual chunk configuration** - Optimize bundle splitting
2. **Configure dependency pre-bundling** - Improve cold start times
3. **Add explicit file extensions** - All import statements

### LONG TERM (Advanced Optimizations)
1. **Dynamic imports for themes** - Code splitting for theme system
2. **Service worker integration** - Cache theme assets
3. **Module federation** - If theme system becomes shared

## Monitoring Standards
- **Bundle size analysis**: Use `npm run build -- --analyze`
- **Dev server startup time**: Should be < 1 second after warmup
- **Hot reload performance**: Changes should reflect in < 200ms
- **Build time targets**: Production build < 30 seconds

## File Size Targets
- **Main bundle**: < 200KB gzipped
- **Theme chunks**: < 50KB each
- **CSS bundles**: < 100KB total
- **Asset optimization**: Images < 500KB each

## Implementation Checklist
- [ ] Remove barrel file exports  
- [ ] Add resolve extensions configuration
- [ ] Configure server warmup paths
- [ ] Add manual chunk configuration
- [ ] Configure dependency pre-bundling
- [ ] Add explicit import extensions
- [ ] Set up bundle analysis
- [ ] Monitor performance metrics