The point of lazy loading is that it delays the startup cost associated with loading a module until the application makes a specific call to load it. This lowers the overall start up cost of the application, but the potential downside is that the module will be a bit slower to get started when the user attempts to access it. By pairing this with a preloading strategy, we are actually having our cake and eating it too by asking Angular to preload the lazy loading module after startup, but before the user would potentially fetch the module.