When your SPA is growing its download time is getting longer and longer. That’s not going hand in hand with better user experience (remainder: that’s why we are doing SPAs). More code means bigger files and when minification isn’t enough for you the only thing you can do for your user is stop making him to download whole app at once. Here lazy loading comes in handy. Instead downloading every file let your user download only files which he need NOW, at this very page.