Излишнее данные после сборки js/css с помощью webpack в файле назначения

Я провожу сборку js/css с помощью webpack в окружении development (т.е. без оптимизаций), ниже строка запуска и вывод оного:

$ webpack --progress --colors -p --display-error-details
yarn run v1.0.2
warning From Yarn 1.0 onwards, scripts don't require "--" for options to be forwarded. In a future version, any explicit "--" will be forwarded as-is to the scripts.
$ "/usr/local/home/majioa/git/dneslov/node_modules/.bin/webpack" "--config" "/usr/local/home/majioa/git/dneslov/config/webpack/development.js" "--progress" "--colors" "-p" "--display-error-details"
Rails root: /usr/local/home/majioa/git/dneslov/
Config file:  /usr/local/home/majioa/git/dneslov/config/webpacker.yml
Env:  development
Hash: d59a55f454013f816eb7
Version: webpack 2.6.1
Time: 4495ms
                   Asset     Size  Chunks                    Chunk Names
  javascripts/webpack/app.js   883 kB       0  [emitted]  [big]  javascripts/webpack/app
  stylesheets/webpack/app.js     4 kB       1  [emitted]         stylesheets/webpack/app
stylesheets/webpack/app.scss  2.12 kB       1  [emitted]         stylesheets/webpack/app
   [0] ./app/webpack/js/behaviors/jquery.1.js 297 kB {0} [built]
   [1] ./app/webpack/js/behaviors/initialize.js.jsx 192 bytes {0} [optional] [built]
   [2] ./app/webpack/css/components (\.scss|\.css)$ 160 bytes {1} [built]
   [3] ./app/webpack/js/behaviors (\.js|\.js.jsx|\.js.coffee)$ 255 bytes {0} [built]
   [4] ./~/pickmeup/css/pickmeup.scss 41 bytes {1} [built]
   [5] ./app/webpack/css/app.js 205 bytes {1} [built]
   [6] ./app/webpack/js/app.js 179 bytes {0} [built]
   [7] ./app/webpack/js/behaviors/debug.js 341 bytes {0} [optional] [built]
   [8] ./app/webpack/js/behaviors/polifill.js 387 bytes {0} [optional] [built]
   [9] ./~/classlist-polyfill/src/index.js 6.14 kB {0} [built]
  [10] ./~/custom-event-polyfill/custom-event-polyfill.js 1.28 kB {0} [built]
  [11] (webpack)/buildin/global.js 808 bytes {0} [built]
  [12] (webpack)/buildin/module.js 506 bytes {0} [built]
Child extract-text-webpack-plugin:
       [0] ./~/css-loader/lib/css-base.js 1.46 kB {0} [built]
       [1] ./~/css-loader!./~/sass-loader/lib/loader.js!./~/pickmeup/css/pickmeup.scss 2.26 kB {0} [built]

Собственно видно, что скрытых модулей нет, однако размер полученного файла (~883) намного больше суммарного объёма составных частей (~313kb). Вопрос, откуда еще 500kb наросло?