Rotten Valley (PC optimization) (Monster Hunter: World)

Faced with a problem in this location, and only there. The game gives a stable 60 fps(is lock) on high settings in loboy point of all the locations in any batch. But one has only to go Rotten in the valley, as there is a drop in fps to 30 in the course of normal study locations, in battle with the same Radovana up to 10 fps(regardless of level settings, whether it is a high or low). Can anyone come across? Don't know whether to sin on the port, because all the other locations stable, nowhere such and close is not found.