Image and Site Optimization and Theme compatibility

I've been reading about page speed and image optimization and have run my site through google page speed insights. I've also regenerated my thumbnails using the viper plugin, tried smush it, and EWWW image optimizer and haven't been able to improve my image loads. I also changed my image settings to those recommended in the theme instructions. Is there a recommended method for Catch Everest Pro to improve my image sizes and loading? Is there a gallery plugin that is recommended for use with this theme? Is there an optimization feature with the theme? Any tips to improve my speed via page speed insights feedback would be most appreciated. Many Thanks! interiorsalvagedesign.com