Optimization Question: Material Slots or UV sets

Hello people!
this is the first time i ever post on the forum so sorry if im in the wrong thread or whatever.

So I´m working on desiding a worklflow for a sci-fi game and im planing to use trim decals (not deferred decals just mapped like a normal trim in the UV) to in a sense “kitbash” object. But its getting to a point where i need to check some choises with all of you of higher knowledge.
So i ofc want a decal layer on meshes to get som more color breakup and make things interesting and grounded. so there is two ways i can add this to the mesh, either I use a second material slot with a deferred Dbuffer decal material applied, or I use another UV channell and use the material layer decal node to make it one material that does it all. Between these choises what is the most optimized if most environment meshes use the setup? Another Uv Chanell or another Material Slot and material.

Thank you for helping if you can =)