index.js

console.log('FooBar')

package.json

{
  "name": "html-webpack-plugin-high-cpu",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "start": "webpack-dev-server"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "dependencies": {
    "html-webpack-plugin": "^2.22.0",
    "webpack": "^1.13.2",
    "webpack-dev-server": "^1.16.2"
  }
}

webpack.config.js

const WebpackHtmlPlugin = require('html-webpack-plugin')

module.exports = {
  entry: './index.js',
  output: {
    filename: 'bundle.js'
  },
  plugins: [
    new WebpackHtmlPlugin() // comment this plugin and cpu drops from 20% to 0.3%
  ]
}