Of the many themes that fails completely on the speed and performance side because they include WpBakery, ISO50 is the only one that is capable to handle it, because it has been coded accordingly and not just thrown it inside. I have used it for 2 years, and never had the smallest issue with it.
It's exactly, what I searched for. A clean and simple but beautiful full screen design to show off my photos.
I love the slideshow feature in fullscreen. It works perfect on desktop and on mobile devices. I could easily customize the theme and could add some custom CSS code for some details I loved to change. So everything works very good for me.