Cache access to process.env

[jnields]

What problem does this feature solve?

Access to process.env is a slow, system-bound call.

After react restructured their project to cache access to process.env, they had a 2.4x - 3.8x performance improvement for server-side rendering,

facebook/react#812

This should also be done for vue, vue-server-renderer, vuex ... anything that accesses process.env.

What does the proposed API look like?

An easy strategy might be to replace references to process.env.NODE_ENV with a reference to a singleton that checks process.env.NODE_ENV.

// foo.js
if (process.env.NODE_ENV !== 'production') {
  // do stuff
}

becomes

// isDevEnv.js
export default process.env.NODE_ENV !== 'production';

// foo.js
import isDevEnv from './isDevEnv';

if (isDevEnv) {
  // do stuff
}