config.js

config.optimization = {
  minimizer: [
    new UglifyJsPlugin({
    parallel: true,
    sourceMap: true,
    }),
  ],
  splitChunks: {
    chunks: 'initial',
    cacheGroups: {
      default: {
        reuseExistingChunk: true,
        minChunks: 2,
        priority: -20,
      },
      vendors: false,
    },
 },
 runtimeChunk: {
  name: 'manifest',
 },
};