Why does it take so much longer for pictures to load on Loveplanet than on Tinder or Badoo?

Question

Android

I'm talking about the sympathy mode in applications, when you sit and massively like everyone in a row for the sake of coincidence)) In Loveplanet, the delay between user pictures is very noticeable. What should be taken into account in your application to make the image loading speed maximum and almost invisible to users? How to use the available Internet channel in the application as efficiently as possible so that the mass download of images is not noticeable?

Answer 1

1) compress pictures on the server in several resolutions and qualities.
2) give the picture to the user based on the fact that 1px of the picture == 1dp of the screen, that is, for the screen of some Nexus 6P 4K, we give the same picture as for the phone screen with 720p. It is not necessary for 4K screens to give a 4K picture.
3) Compress with JPEG quality 82% (I did this, you can choose your quality).
4) Be sure to do prefetching: download several images at once in advance. Try to make the algorithm smart and aggressive: if the user looks at an unloaded picture, do not download anything else but it. And if he has already scrolled through the picture, which has not loaded, then stop its loading.
5) You can get confused and improve the quality of the picture when the user is not sitting on a metered network