performance-profiling

name	performance-profiling
description	Profile and optimize CampusOS performance. Use when investigating slow pages, reducing bundle size, optimizing memory usage, or improving Lighthouse scores.

Performance Profiling

When to Use

• Page loads slowly
• Bundle size exceeds budget
• Memory usage increasing
• Lighthouse score below target

Procedure

1. Bundle Analysis

ANALYZE=true pnpm build
# Check build output for large chunks
# Look for duplicates, unused libs, large packages

2. Memory Profiling

node --inspect=9229 backend/src/index.js
# In Chrome: chrome://inspect
# Take heap snapshots before/after operations

3. Database Query Profiling

// Enable Mongoose debug logging
mongoose.set('debug', true);

// Use .lean() for read-only queries (skip hydration)
const vendors = await Vendor.find({ status: 'active' }).lean();

// Add indexes for frequently filtered fields
vendorSchema.index({ category: 1, status: 1 });

4. Frontend Profiling

npx lighthouse http://localhost:3000 --output=json

Next.js optimizations:

• Use next/image for automatic image optimization
• Dynamic imports for heavy components
• Server Components by default (no 'use client' unless needed)
• Geist fonts via next/font/google (no external font loading)

5. Optimization Workflow

# 1. Baseline
pnpm build

# 2. Identify bottleneck (bundle, query, memory)

# 3. Optimize

# 4. Measure improvement
pnpm build  # Compare output sizes

Quick Reference

pnpm build                    # Production build
ANALYZE=true pnpm build       # Bundle analysis
npx depcheck                  # Unused packages
NODE_OPTIONS="--inspect" pnpm dev  # Profile in dev

Common Issues

Issue	Solution
Bundle increased	pnpm why <pkg> for dupes; dynamic imports for routes
Slow queries	Add indexes; use .lean(); check N+1 queries
Memory leak	Close DB connections in tests; check setInterval
Build time high	Use Next.js webpack (default); cache aggressively