Huge memory usage with template unreal map

Hello, i am currently doing an AI project using the latests version of the U4 engine (4.7.5) and i decided to reuse the top down game mode map for what i need.

On my map i have 4 areas which are 4 copies of the original template but without the columns and the light mass and some other things i have no need for, i am looking to have something simple and fast and not pretty.

When i build my project the ram usage goes to about 10GB and he takes some minutes to process everything.
To note i have a gtx970 , i7 and 16GBS ram so it feels like i’m using a super strong machine and having problems with something that shouldn’t give at all.

I tested getting a brand new template and it used around 2.5GB ram. I copied once to get 2 copies on the same map and the ram doubled. Thus i figured that the 10GB come from the 4 areas which are 4 copies…

So my problem here is that i have these empty and super simple polygon scenes, but they are super resource intensive to build. Any help? I decided to use the template because it is super simple but can’t understand why increasing the map size is so resourcefull