Blueprint or FBX Prefab?

Hi, I have individual assets compiled within my content library and ready to go. I’m going to create prefabrications with these.

Which is more efficient on the engine? Blueprint prefabs or FBX prefabs as combined objects using the materials already within the content library?

All depends if you wish to use some of the assets seperately (then use blue prints) or if you are just going to use the set as a single main piece (then group them together then export as one FBX). I don’t think it really matters in terms of performance as you are calling the same amount of textures/polycount no matter what.