Thanks for the bug report, I'm aware of this and it's from the new water caustics 😕 if you turn them off it will fix this problem. I'm still trying to find out why this is happening but it's proving hard cause on my PC it's all fine but on my laptop with a gtx 880m I also get this, it could be a driver issue or the architecture of the video cards as my gtx980 is fine with it but I really don't know at this stage.
It ain't a driver's issue i tell ya, cause i roll my driver way back to 259.06 which released last Dec, and the problem still there.
so maybe it's the shader's problem it self?\
here's my spec: