Strange effect with R.I.S.

Hi!
I used your plugin for this site: http://www.casadeigelsi.com.
when I change the page of the site, there is a strange effect: they appear the 4 images added to the slide one under the other and then regroup and begin to fade in a regular.
is it possible to eliminate this problem? and how?
Best regards

https://wordpress.org/plugins/responsive-image-slider/