react-dom blowing out webpack bundle size MASSIVELY

Question

This has got to be one of the strangest issues with webpack i have ever come across...

Check out this bundle breakdown: react 116.01KB - fair enough

react-dom 533.24KB - seriously WTF

I thought it may be a corruption in my dependencies but nuking node_modules and reinstalling doesn't have any effect. I guess it's something to do with the way webpack is bundling it but i'm lost for ideas. The way i'm handing .js imports is pretty stock standard.

// webpack.config.js
const path = require('path');
// const BundleAnalyzerPlugin = require('webpack-bundle-analyzer').BundleAnalyzerPlugin;
const ExtractTextPlugin = require('extract-text-webpack-plugin');
const Dashboard = require('webpack-dashboard');
const DashboardPlugin = require('webpack-dashboard/plugin');

const dashboard = new Dashboard();

module.exports = {
  context: path.join(__dirname, 'src'),
  entry: {
    bundle: './index.js',
  },
  output: {
    filename: 'bundle.js',
    path: path.join(__dirname, 'build'),
  },
  module: {
    rules: [
      {
        test: /\.html$/,
        use: 'file-loader?name=[name].[ext]',
      },
      {
        test: /.scss$/,
        use: ExtractTextPlugin.extract({
          fallback: 'style-loader',
          use: [
            'css-loader',
            'postcss-loader',
          ],
        }),
      },
      {
        test: /\.js$/,
        exclude: /node_modules/,
        use: 'babel-loader',
      },
    ],
  },
  plugins: [
    // new BundleAnalyzerPlugin(),
    new ExtractTextPlugin('styles.css'),
    new DashboardPlugin(dashboard.setData),
  ],
  devServer: {
    quiet: true,
  },
};

// .babelrc
{
  "presets": [
    "react",
    "es2015"
  ],
  "plugins": ["transform-object-rest-spread"]
}

Answer 1

http://elijahmanor.com/react-file-size/

In v15.4.0 the file size of react-dom grew from 1.17kB to 619.05kB. Which means my webpack setup isn't doing anything wrong bundling files. The reason why this module grew so large is because code was transferred from the react module.