To optimize to the water in 1.5 you guys should try and do what Planet Coaster has done. Make the water 2 planes, one above the other. Then give them a reflection map and a water texture, below the water let there simply be nothing. The game is only rendering those to flat surfaces and their textures. Then you have good looking water with barely any lag.
Here is what water looks like in planet coaster and it causes no lag.