Skip to content

import "typescript" slower than require("typescript") due to cjs-module-lexer overhead #59913

Description

@chenjiahan

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.

Image

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

Activity

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Metadata

Metadata

Assignees

No one assigned

    Labels

    No labels
    No labels

    Type

    No type

    Projects

    No projects

      Milestone

      No milestone

      Relationships

      None yet

      Development

      No branches or pull requests

      Issue actions