I suggest using a gallery plugin that will show thumbnail images and then load the large image after the thumbnail is clicked.
I’ve seen this one used.
Also, in most cases, 4000px images are not needed if your goal is only to let people see your photography. 1200px wide is plenty large enough.
I would also suggest making them .jpg images and compressing them to about 70% in photoshop, instead of using smush – if quality is a concern.
Downloading 14+ MB of files just to show the webpage is a very expensive process.