title: delay modules preload after first app rendering
body: <p>I'm currently working on a single page app.
  in the main page several card are displayed.
  These cards may be enabled or disabled.
  If disabled, only the title of the card is displayed.
  If enabled, the title plus the content (which is lazy loaded) of the card is displayed
  By default all cards are displyed and disabled.
  According to user's dossier, some cards may be active when loading the page.</p>
  
  <p>Currently, I didn't set any preloadingStrategy, thus, when loading the page, only the content of active card are loaded.</p>
  
  <p>I have tried to set preloadingStrategy to preloadAllModules, it works fine, but it slow down the app start up. Actually, the content of active cards appear slower as all modules are loaded at the same time.</p>
  
  <p>=> What I want is :
  1. load the app
  2. load the content of all active cards
  3. preload all other modules that are not shown at startup</p>
  
  <p>=> Some kind of delaying the preload after first rendering</p>
  
  <p>=> Do you think that its possible ?</p>
  
  <p>Thanks in advance for your feedback</p>