unity3d - Multiple materials or texture on low poly meshes? -

i'm creating low poly environment in blender , importing unity. in blender have mesh few materials assigned different faces. know 2 approaches export unity: export materials or render texture , assign object. question is: option better in case of performance?

from read using multiple materials worse in case of performance(correct me if i'm wrong), when add texture imported object still shows uses few materials in mesh renderer. importing wrong or should these?

there screenshots of mesh renderer before , after add texture:

multiple materials performance killing. if game tiny, these not on issue. not suggested anyways.

when exporting single texture, remember deleting additional materials in blender. or can set value of size under materials 1. case remove materials keeping first 1 or can set textured 1 there , remove others well.