I just wanted to add, that for me personally CWG has some of the worst performance out of all maps, however, just in specific areas and/or viewing angles... came here in search for others and found this topic. I have never seen the issues in the north, but for myself they manifest strongly when flying:: Instant Action, F-16C, Free Flight, drop down into the city of Kassel and follow the river north, flying low. Without exception, every single time I will begin to come across areas where the FPS are essentially cut in half. There isn't anything specific in these areas either, many trees as anywhere else, river, villages... but as soon as I look away from these areas or get past them in the jet, everything is back to normal.
I fly in VR, 64GB RAM, RTX4080, fps locked to 75, no smoothing, no vsync (obviously). So, in general, this seems to be happening to all kinds of system configurations.
I will try adding a pagefile, generally I had this turned off because I have never encountered a game that would actually utilize the entire 64GB of RAM and adding 64GB of a pagefile seems like a waste of disk space but who knows, maybe it helps. edit: Apologies, I was wrong, I had the pagefile set to be managed by Windows at 4096.