Performance Penalties, What Are The Factors That Affects It?

In light with Epic’s topic on How to Improve Game Thread CPU Performance. I needed to ask what are other factors that could affect my project’s performance in the long run.

My basic knowledge in this was Mesh Count, I know that the more mesh my model has, the more resources my project will consume.

In UDK 3, it is said that the more Materials assigned to an Asset, the higher the performance penalties it get but if we used Modular Assets to build the same Asset, it doesn’t get any performance penalties (at least this is what I remember). I came late in UDK, so I was unaware of some or most the technical issues about performance penalties, anyway, does this also applies in UE4?

If there is at least a link that you could provide for me to read about this topic, I’ll be happy to read it.

Thank you…