Portfolio Loads slowly

So, I am not sure if I am doing this in the best way possible, but I am building lightbox galleries using this plugin with each photograph being a different “project”. This seems to make the loading time for the page really long as the plugin scrambles to arrange the images on the page. Is there any way to speed this up? Or possible have a loading screen until it’s done? Let me know. Maybe I am using the plugin wrong. Thanks. Site example is below.

http://www.peterbrannanphotography.com/commercial-work/

https://wordpress.org/plugins/portfolio-gallery/