Problem

There are two module system you can choose in Node.js:

• Importing modules using require, and exporting using module.exports and exports.foo
• Importing modules using ES6 import, and exporting using ES6 export.

Are there any performance benefits to using one over the other? Is there anything else that we should know if we were to use ES6 modules over Node ones?

Answer

At the time of writing this, there is no JavaScript engine yet that natively supports ES6 modules. If you are using Babel, Babel actually converts import and export declaration to CommonJS (require/module.exports) by default anyway. So even if you use ES6 module syntax, you will be using CommonJS under the hood if you run the code in Node.

require() from NodeJS (CommonJS)

• You can have dynamic loading where the loaded module name isn't predefined /static, or where you conditionally load a module only if it's "truly required" (depending on certain code flow).
• Loading is synchronous. That means if you have multiple requires, they are loaded and processed one by one.

import from ES6

• You can use named imports to selectively load only the pieces you need. That can save memory.
• Import can be asynchronous (and in current ES6 Module Loader, it in fact is) and can perform a little better.

In addiion, the require isn't standard based. It's is highly unlikely to become standard now that ES6 modules exist. In the future there will be native support for ES6 Modules in various implementations which will be advantageous in terms of performance.