Pull request #2976 added support for require not looking outside of the current application when loading modules by patching Module._nodeModulePaths and pulling in some code from node's own module.js implementation.

Node's implementation got some great improvements via nodejs/node#5172 and this pull request seeks to use those improvements via post-processing the results of the default implementation instead of reimplementing the method fully.

• Add specs for previous behavior
• Use default Module._nodeModulePaths implementations and filter results in patched version
• Profile it 🏇

This was profiled by calling Module._nodeModulePaths using 1,000 paths that were all inside the app's resources path so the filtering is happening on every call.

It looks to be a 50-75% speed improvement, results below.

var path = require('path')
var Module = require('module')
var paths = require('./paths')

module.exports = function () {
  var start = Date.now()
  var count = 0
  var total = 0
  for (var i = 0; i < paths.length; i++) {
    count++
    total += Module._nodeModulePaths(paths[i]).length
  }

  var time = Date.now() - start
  console.log(`${paths.length} paths resolved to ${total} search paths in ${time}ms`)

}

Before