You know what 1CMAddox after IL2, FB, AEP and now Pacific fighters.
STILL have problems with the water effect after basically 4 games.
In AH its a NEW effect, it will take some adjusting to become useable.
Personally i have no fps loss with it, but i switched it off because it looks awful at alt.
As others said it gives the impression of vid screen "snow" not nice, however at low alt and near to your plane it does look good apart from an awful colour.
Not black here but a real deep blue, totally unrealistic but then the terrain colours have been a subject of much discussion in the past.