Images loading one on top of the other, on slow connection

When the Internet connection is slow, the images can be seen loading one on top of the other.
It can be simulated in this flickity demo, choosing the Chrome Mid-tier mobile console and clearing the cache: https://codepen.io/desandro/pen/jrGWRQ

Can it not be seen like this, but more elegant?

Thank you,
Bogdan

Start by reproducing the behavior in the linked CodePen demo with Chrome's Mid-tier mobile throttling and a cleared cache. Done should mean images no longer visibly load on top of one another during a slow connection, though the issue does not identify a source file or test.

Written by the indexing model from the issue text.