This is an awesome feature which improves the overall performance and speed of loading
because in this way not all the thumbnails are loaded and displayed at once. For
example if you have a total of 120 thumbnails you can show them in sets of 50 thumbnails,
and so initially in the grid the first set of 50 thumbnails are loaded and displayed,
and when the "load more thumbnails" button is pressed the next set of 50 thumbnails
are loaded and displayed, and finally when the "load more thumbnails" button is
pressed again the 20 remaining thumbnails are showed. The number of thumbnails to
load per set is customizable, it does not have to be 50 it can be any number that
you consider. This feature is optional, if it is disabled all thumbnails are loaded
and displayed.