Lot of Compiling Shaders

I’d like to ask if someone can help me about a lot of compiling shaders.
I have a material in my landscape: there are some textures with samples (for layers with grass …) and simple textures for painting the map. Kind of 7 textures total.
At the beginning of the map I didn’t have this but now the amount of shaders increased incredibily.Even when I build, it doesn’t change. I have sort of 3500-5000 compiling shaders when I do small changes in my material, it takes long minutes…
How can I resolve this?
Here a pic of the map in progress (I begin unreal since two weeks so I have basics only):…nshot00050.png