perf: 140ms improvement: Hook into require() to modify how certain modules load

package.json

@@ -29,6 +29,7 @@
     "iso-639-1": "^1.2.1",
     "languagedetect": "^1.1.1",
     "location-history": "^1.0.0",
+    "lodash.merge": "^4.6.0",
     "material-ui": "^0.15.4",
     "mkdirp": "^0.5.1",
     "musicmetadata": "^2.0.2",
@@ -102,7 +103,7 @@
     "package": "node ./bin/package.js",
     "prepublish": "npm run build",
     "start": "npm run build && electron .",
-    "test": "standard && depcheck --ignores=buble,nodemon,gh-release --ignore-dirs=build,dist && node ./bin/extra-lint.js",
+    "test": "standard && depcheck --ignores=buble,lodash.merge,nodemon,gh-release --ignore-dirs=build,dist && node ./bin/extra-lint.js",
     "update-authors": "./bin/update-authors.sh",
     "watch": "nodemon --exec \"npm run start\" --ext js,pug,css --ignore build/ --ignore dist/"
   }

src/renderer/main.js

@@ -1,3 +1,22 @@
+/**
+ * Perf optimization: Hook into require() to modify how certain modules load:
+ *
+ * - `lodash/merge` (used by `material-ui`) causes 119 require() calls at startup,
+ *   which take ~100ms. Replace it with `lodash.merge` which is equivalent.
+ *   See: https://github.com/callemall/material-ui/pull/4380#issuecomment-250894552
+ *
+ * - `inline-style-prefixer` (used by `material-ui`) takes ~40ms. It is not
+ *   actually used because auto-prefixing is disabled with
+ *   `darkBaseTheme.userAgent = false`. Return a fake object.
+ */
+let Module = require('module')
+const _require = Module.prototype.require
+Module.prototype.require = function (id) {
+  if (id === 'lodash/merge') id = 'lodash.merge'
+  if (id === 'inline-style-prefixer') return {}
+  return _require.apply(this, arguments)
+}
+
 console.time('init')
 
 const crashReporter = require('../crash-reporter')