---

name: backend-latency-profiler-helper description: Identifies API latency hotspots and bottlenecks with profiling tools, slow endpoint detection, suspected causes, and fix roadmap. Use for "latency profiling", "performance bottlenecks", "slow APIs", or "backend performance".

Backend Latency Profiler Helper

Find and fix API performance bottlenecks.

Slow Endpoint Detection

Copy// Middleware to track latency
app.use((req, res, next) => {
  const start = Date.now();

  res.on("finish", () => {
    const duration = Date.now() - start;

    if (duration > 1000) {
      logger.warn(
        {
          endpoint: req.path,
          method: req.method,
          duration_ms: duration,
          userId: req.user?.id,
        },
        "Slow request detected"
      );
    }
  });

  next();
});

Top Slow Endpoints

Copy-- Query from logs
SELECT
  endpoint,
  AVG(duration_ms) as avg_ms,
  MAX(duration_ms) as max_ms,
  COUNT(*) as requests
FROM request_logs
WHERE created_at > NOW() - INTERVAL '1 day'
GROUP BY endpoint
HAVING AVG(duration_ms) > 500
ORDER BY avg_ms DESC
LIMIT 10;

Suspected Causes

Copyinterface PerformanceBottleneck {
  endpoint: string;
  avgLatency: number;
  suspectedCauses: string[];
  fixPriority: "high" | "medium" | "low";
}

const bottlenecks: PerformanceBottleneck[] = [
  {
    endpoint: "GET /api/users/:id",
    avgLatency: 2500,
    suspectedCauses: [
      "N+1 query fetching user orders",
      "No database index on user_id",
      "Expensive JSON serialization",
    ],
    fixPriority: "high",
  },
];

Fix Roadmap

Copy# Performance Fix Roadmap

## Week 1: Quick Wins

- [ ] Add database indexes
- [ ] Enable response caching
- [ ] Fix N+1 queries

## Week 2: Medium Effort

- [ ] Optimize slow database queries
- [ ] Implement Redis caching
- [ ] Add connection pooling

## Week 3: Long-term

- [ ] Database query optimization
- [ ] Service decomposition
- [ ] CDN integration

Output Checklist

• Slow endpoints identified
• Causes analyzed
• Fix roadmap created
• Monitoring configured ENDFILE