Parktaehyoung I see, thank you for explaining the situation. This is just my guess, but I think the problem the programmer experienced was caused by using slot colors in the wrong way. Sometimes users don't know how to hide attachments, so they set the alpha value of the slot color to 0 to hide the attachment. However, when you do this, even if the attachment is not visible on the screen, the image is still drawn, resulting in unnecessary performance cost. (The correct way to hide an attachment is to add a slot attahcment key to hide it.)
Making the slot color black should not affect performance, but if you are duplicating and using a very complex mesh, the number of vertices may increase too much, so you may want to simplify the mesh attachments for the outline by reducing the number of inner vertices as much as possible.
