Combining textures

Is there any way to combine textures at load time? I’m wanting to apply the effects of blending 3 textures together when the character is loaded. I know I can just use a material and set 3 different textures, but for performance reasons I want to combine them. Is there anything built in for this similar to FSkeletalMeshCombiner for textures? Or is there a way to access pixels so I can do it manually?