title: Webpack: what are modules with no loaders? How to optimize them?
body: <p>I'm using <code>speed-measure-webpack-plugin</code> to measure the performance of my Webpack builds, and something is mysterious to me : when cold booting my dev build, I see that <code>modules with no loaders</code> is by far the most common type of module, and also the type of module that takes the longest to process :</p>
  
  <pre><code> SMP  ⏱  Loaders
  modules with no loaders took 48.51 secs
    module count = 2963
  typings-for-css-modules-loader, and
  postcss-loader, and
  less-loader took 41.81 secs
    module count = 95
  ts-loader took 39.55 secs
    module count = 488
  babel-loader took 4.12 secs
    module count = 4
  css-loader, and
  postcss-loader took 3.91 secs
    module count = 1
  url-loader took 1.13 secs
    module count = 10
  pegjs-loader took 0.723 secs
    module count = 2
  style-loader, and
  typings-for-css-modules-loader, and
  postcss-loader, and
  less-loader took 0.157 secs
    module count = 95
  html-webpack-plugin took 0.045 secs
    module count = 1
  style-loader, and
  css-loader, and
  postcss-loader took 0.002 secs
    module count = 1
  </code></pre>
  
  <p>My questions are: what exactly are modules with no loaders? Is there a way to list all those modules with no loaders so I can see where they come from, and what can be done about them?</p>
  
  <p>I'm suspecting they come from <code>node_modules</code> dependencies, but I'm not sure what to do about it....</p>