1. Firstly, you can use our Image Optimization functionality (IMAGE OPTIMIZE and TRANSFER TO CDN). You can find more information here https://supsystic.com/docs/image-optimization
2. Secondly, as soon as your gallery has many images, it will be useful to enable “Load More” button https://prnt.sc/foai7o on the Main tab of gallery settings. Notice that you have a possibility to edit it.