My framerate drop every 3 seconds from 120fps to 0fps?

Hey, i have a big problem
I do cinematics and with photo-realistic assets from the megascans library. Now recently my framerate drops every like 3 seconds from 120 to 0?
I assigned 8GB RAM to my Unreal Editor. My GPU is a Nvidia Geforce GTX 1060 and my cpu a Intel Core i5 6600K 4x 3.50GHz.
My ping drops also from 8ms to 77ms.
Please can someone help me to fix this issue?

first of all megascans are not supposed to be used for games they are too high poly and unoptimized
what might be causing this is some process that interacts with the high res model that causes this random lag for example saving all the data in the level etc