While trying to build my custom & realistic open world on UEFN, I noticed something very frustrating: the more I add a quantity of elements on Foliage/Landscape/Splines, the more the size of my Level as well as Materials, and more particularly Shaders, increase!
All the elements are managed by a total of about 10 Master Materials and many instances. All the textures/meshes are also well optimized; out of 20% of the current size of my project, only 5% concerns all the elements placed by me directly, while about 5% are reserved for the Level & almost 10% ONLY for Shaders! (More details of the project size below)
At this point, if I continue to enlarge my map, the shaders and the level together will use more than 50% of my project! 
So I wanted to know if you have any tips to optimize & reduce the size of shaders, I am interested and I am convinced that it will help more than one in the design of open world inside Fortnite!