`import "typescript"` slower than `require("typescript")` due to `cjs-module-lexer` overhead

Version

• Node.js v24.8.0
• Node.js v22.18.0

Platform

Observed on macOS (x64), but likely reproducible on other platforms.

Description

When loading typescript, using import is ~100ms slower than require.

This seems to come from the cjs-module-lexer step Node.js runs for CommonJS packages. Since typescript itself is CommonJS, require avoids the overhead and is noticeably faster.

Reproduction

https://github.com/chenjiahan/nodejs-repro-require-import-typescript

// import.mjs
import typescript from "typescript";

console.log(typescript);

// require.cjs
const typescript = require("typescript");

console.log(typescript);

Example results (macOS, Node.js v24.8.0):

# ~200ms
time node ./import.mjs

# ~100ms
time node ./require.cjs

Ref

• https://x.com/matteocollina/status/1968303799271047230 @mcollina

从链接的复现开始，使用提供的计时命令在 Node.js v24.8.0 和 v22.18.0 上比较 import.mjs 与 require.cjs。调查针对 CommonJS 包 typescript 报告的 cjs-module-lexer 开销；当性能差异得到复现和解释，并且任何拟议的范围都得到记录时，即视为完成。