I love the color of your deep water.
Are you coloring the terrain under your water depth, and then just using refraction/reflection( I do this but don't know if this is best vs coloring based off depth map in the water shader)? I keep getting sharp, random declines in my fps. I didn't get that when I have FPS unlimited.
With unlimited FPS I get from 100-130 FPS on my cheap laptop. When I use Vsync I usually get 60, but I sometimes drop to 40. I even use a shader that does not color the terrain when making the depth map( no idea if this helps, but it seems like it does not).
Just curious, if you have the same issue.
edit: I love these types of games, and I want to buy it asap