title: export all package from one file, and then import them from this uniq source
body: <p>I would like to export all my package from one single file, let's say exportAll.js and then across the code I may be able to import the one I need per file using something like</p>
  <pre><code>import { package1, package2 } from '../exportAll.js'
  </code></pre>
  <p>However I am concerning about the performance impact. I do believe after once import, Javascript save the reference for future import. However I also believe Javascript will first import all files into exportAll.js when I want to use only package1 and package2 and so, it may slow down the loading process of the first page who import anything from exportAll.</p>
  <p>Can you help me to understand if this is bad for performance or even if this is bad practice for any other reason ?</p>