Its the hero tree , there is only that one giant tree in the middle of the map , the rest of the objects have way less polys 
I have 20 GB of RAM , is that not enough ?
Zbrush and blender load the asset with no problem at all in under 20 sec, why does UE4 editor take more than 20 minutes for the same asset ??
Shouldnt they be at least in terms of loadingspeed for assets comperable,even if they are used for different purpose otherwise?