I have big performance drops around the tunnel in Nasdara (I mean the city, not the entire map), in it's underground area and even above it.
I'm assuming that this is because of the number of assets in this area. This also seems to be a new issue coming from the update that released a few days ago. When I was in the area in the Badlands release version, my FPS was fine.
I've provided a rough map of where the issues starts.