How to load multiple images efficiently on web page

I am working on an app which loads around 50 images in single page using angular [src] property binding. What is the best way to optimize this process? I'm not sure but does the images load sequentially or are they processed asynchronously with Angular? What kind of optimizations browser an make? I'm on Angular 4.4 version.

I heard about forkJoin in Angular. Can it be helpful?