FPS drawdowns in scene mode at max. water quality at night (Grand Theft Auto 5)

Hi, the problem is this: in the usual story mode, when you just ride around the city or do it. missions, there is a strange joke - when the clock on the phone in the game shows the time from 07:00 to 19:00 - the fps is stable above 60, and when the clock shows from 19:00 to 07:00, that is, at night in the game, drawdowns are up to 40 fps, but in the daytime there is no such thing! I noticed that this is due to the quality of the water, if you put it on the standard, then the drawdowns pass, but at high or very good. high - that's it. in FAR KRAY 3 the same way, if the water is low - there are no drawdowns, and at high - the same joke. someone else came across? why is that? is it a bug or what ??? config: ryzen 5 1600 stock, rx 570 4 gb, 16 gb ram, win 10 pro, ful hd monitor, ssd; firewood and renewals are all the latest ... and a joke - only the quality of water affects, if everything else is reduced to a minimum, there will still be subsidence ... the same should not be !!!