Hi, i’m creating my landscape material. i would need 6 blended textures. it it ok in term of performance. isn’t it a bit too much
Six layers should be fine 
is that normal that it takes a lot for the shaders to compile, when creating a layer info in world composition
the answer is here. you can have up to 16 layers per component. so as long as you stay sober while filling the components, you may have an almost endless number of textures on your landscape