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What is the perf_hooks module and how do you measure performance?

Q: What is the perf_hooks module and how do you measure performance?

**TL;DR.** node:perf_hooks exposes **high-resolution timing**: performance.now() , mark() / measure() for named spans, and a PerformanceObserver to collect entries asynchronously. It also surfaces **event-loop utilization** and **GC** timing — the building blocks for instrumenting your own performance metrics. mark('A') work… mark('B') <rect class='d-box' x=

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Understand the problem

High-resolution timing, marks/measures, and observers.

nodejsperformanceperf-hooksobservability

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Measure a span + observe entries

import { performance, PerformanceObserver } from 'node:perf_hooks';

new PerformanceObserver((list) => {
  for (const e of list.getEntries()) console.log(e.name, e.duration.toFixed(2), 'ms');
}).observe({ entryTypes: ['measure'] });

performance.mark('db:start');
await query();
performance.mark('db:end');
performance.measure('db', 'db:start', 'db:end');

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