Or is it the same or nearly the same as if those faces were deleted? Trying to figure out if it is worth deleting faces that would be underneath clothing versus just making them invisible/transparent. Thank you for any help!
Yes they still need to be evaluated.
Parts of the mesh that are occluded by fully opaque surfaces shouldn’t be a big concern though.
Indeed, making them masked or transparent can actually make it more expensive than if it was just left alone. To be more specific, opaque faces that are covered by other opaque faces will be evaluated by the vertex shaded in order to determine their depth. Only the surface closest to the camera will need to have the pixel shader evaluated.
It’s good practice to remove the underlying geometry because of the potential for clipping moreso than the cost of shading.