(Very) Poor Performance on Small Island, USA

Hey guys,
I've been experiencing bizarre performance behavior out of my game while roaming around small island.
FPS drops into the low 30s but GPU util never goes past 60ish%.
On some parts of the map though with the same or even less util I easily get into the 60ies.
Specs:
7900XTX (1080p)
7950X

 

West coast has the same behavior, it doesn't go full util.
Utah though goes full util.
Whats going on