replit-performance-tuning

# Replit Performance Tuning ## Overview Optimize Replit app performance across the entire lifecycle: cold start reduction, Nix environment caching, build speed, runtime memory management, and deployment configuration. Replit containers have resource limits — efficient usage is critical. ## Prerequisites - Replit app deployed or running in Workspace - Understanding of `.replit` and `replit.nix` - Access to deployment monitoring ## Instructions ### Step 1: Reduce Cold Start Time Autoscale deployments scale to zero when idle. First request triggers a cold start (10-30s). Minimize it: ```typescript // 1. Lazy-load heavy modules — only import when needed // BAD: imports everything at startup import { heavyAnalytics } from './analytics'; // 500ms import { imageProcessor } from './images'; // 300ms // GOOD: import on demand app.get('/api/analyze', async (req, res) => { const { heavyAnalytics } = await import('./analytics'); res.json(await heavyAnalytics.process(req.query)); }); // 2. Defer non-critical initialization let dbPool: Pool | null = null; function getDB(): Pool { if (!dbPool) { dbPool = new Pool({ connectionString: process.env.DATABASE_URL, ssl: { rejectUnauthorized: false }, max: 5, // Keep pool small for faster init }); } return dbPool; } // 3. Start server immediately, initialize after const app = express(); const PORT = parseInt(process.env.PORT || '3000'); app.listen(PORT, '0.0.0.0', () => { console.log(`Server ready...