Node.js `perf_hooks` Core Module (npm `perf_hooks` placeholder)

The `perf_hooks` module is a fundamental, built-in Node.js core module that provides performance measurement APIs based on the W3C User Timing and Performance Timeline specifications. It enables developers to instrument and observe Node.js application behavior with high-resolution timers, performance marks, measures, and observers. Key APIs include `performance.now()`, `performance.mark()`, `performance.measure()`, `PerformanceObserver`, and `eventLoopUtilization()` for monitoring event loop delays. This functionality is part of Node.js itself and does not require a separate npm installation; it is stable across all supported Node.js versions (currently 18.x LTS, 20.x LTS, 22.x LTS, with new versions released regularly). Critically, the npm package `perf_hooks` (version 0.0.1) mentioned in the metadata is a long-abandoned placeholder, last published nine years ago. Despite having high weekly downloads, it offers no actual functionality and should *never* be installed or used. Users seeking performance tooling should rely exclusively on the `node:perf_hooks` core module.