Mutex causes non bottleneck performance problem in unreal engine 4

I noticed that unreal engine lags or become sluggish when there are a lot of objects in the scene, in low end pcs this maybe explainable but not for mid to high end ones.

Try to open Infiltrator demo, yhea its pretty demanding scene, however I noticed that the slugishness was not caused by strugling SSD, CPU or GPU, not even bandwidth! I confirmed this by checking system monitor and Nvidia gpu checking tool, nothing is getting past beyond 30%, not even on a per core basis!

Clearly, there must be something unusuall happening in the engine, its not that unreal engine is hardware demanding but there might be a programming problem that affects all dev platform!

I think mutexes and for-loops in UE4 are causing the problem, I have seen several program with the same issues and improving those parts fixed it!

Solving this would really become a huge boost to UE4, cause game dev could do more and enables them to create much much better games due to improved performance. The cinematography industry could also take this as a huge advantage.