FPS issue caused by high water quality

Seems like high water quality totally ruins the FPS. Pictures below, you can see the FPS furiously jumping between 200+ to under 10 in my hideout and being fine near land. It is not temporary loading lag or smth. The closer to the water I get the worse it gets, pretty much stable 10FPS (beginning of graph on last picture).



My specs:
OS: Windows 10 Pro
GPU: GeForce GTX 1080 Ti Gaming Trio (11 GB)
CPU: AMD Ryzen 5 3600x
RAM: 16GB
The game is also on SSD.

Regular area performance for comparison:


Broken bridge near water:


Changing water quality to low changes 10FPS to 270.