How do I fix runtime "Failed to compile Material Instance" and "Building adjacency information"?

Legacy UDK Content Creation and Design
2

Yeah, it takes about 6 seconds each time the game tries to compile a material instance at runtime. I have a level that has 4 of these in them. It spends 24 seconds trying and failing to compile material instances, then it saves LocalShaderCache-PC-D3D-SM3.upk. How do I stop that?