Make Your CLI Tool 10x Faster: Performance Patterns for Node.js

Make Your CLI Tool 10x Faster: Performance Patterns for Node.js Users notice slow CLI tools. If --help takes a second to appear, if a simple check takes 3 seconds when it should take 300ms, if startup feels sluggish — users will find alternatives. Speed is a feature. This article covers the performance patterns that make the biggest difference in Node.js CLI tools: lazy imports, parallel I/O, streaming over buffering, caching, and startup optimization. 1. Lazy Imports: The Biggest Win The #1 performance killer in CLI tools is importing everything at startup. If your tool has 10 commands but only runs one at a time, why load all 10? // SLOW: imports everything on startup (~500ms) import lighthouse from ' lighthouse ' ; // Heavy module import * as chromeLauncher from ' chrome-launcher ' ; import Table from ' cli-table3 ' ; import { createCanvas } from ' canvas ' ; // C++ addon, slow to load // FAST: only import what's needed for the specific command (~50ms) program . command ( ' audit <u