As per the Crash on Settlement Guide I'm making a bug report of a potential memory overload. As the title suggests when I fast travel to either Sanctuary or Red Rocket (Both using the RoTC City Builder), I can move around for a few seconds before the game CTD. Approaching the settlements by foot doesn't cause any crashes. Additionally both of these settlements are just the base RoTC provided City Plans at level 1, I haven't added any additional settlement objects. I'll be looking into the Performance Guide should it continue. Trying just placing down Fast Travel mats for now.