performance-profiler

Performance Profiler

Identify and resolve performance bottlenecks in your code.

When to Use

• Application is slower than expected
• Looking for optimization opportunities
• Memory usage is growing unexpectedly
• Users report slow response times
• Preparing for load testing

Performance Investigation Workflow

┌─────────────────────────────────────────────────────────────┐
│ 1. MEASURE - Baseline current performance                   │
├─────────────────────────────────────────────────────────────┤
│ 2. PROFILE - Identify where time is spent                   │
├─────────────────────────────────────────────────────────────┤
│ 3. ANALYZE - Understand why it's slow                       │
├─────────────────────────────────────────────────────────────┤
│ 4. OPTIMIZE - Make targeted improvements                    │
├─────────────────────────────────────────────────────────────┤
│ 5. VERIFY - Confirm improvement without regression          │
└─────────────────────────────────────────────────────────────┘

Measurement Techniques

Basic Timing

// Simple timing
console.time('operation');
await slowOperation();
console.timeEnd('operation'); // operation: 1234ms

// More precise
const start = performance.now();
await slowOperation();
const duration = performance.now() - start;
console.log(`Took ${duration.toFixed(2)}ms`);

Structured Performance Logging

class PerformanceTracker {
  private marks = new Map<string, number>();

  mark(name: string): void {
    this.marks.set(name, performance.now());
  }

  measure(name: string, startMark: string): number {
    const start = this.marks.get(startMark);
    if (!start) throw new Error(`Mark ${startMark} not found`);

    const duration = performance.now() - start;
    console.log(`[PERF] ${name}: ${duration.toFixed(2)}ms`);
    return duration;
  }
}

// Usage
const perf = new PerformanceTracker();

perf.mark('start');
await fetchData();
perf.measure('fetchData', 'start');

perf.mark('afterFetch');
await processData();
perf.measure('processData', 'afterFetch');

perf.mark('afterProcess');
await saveResults();
perf.measure('saveResults', 'afterProcess');