FPS drop - water reflection?

[Reflected]

Hi,

 

I'm getting a decent 40+ FPS all the time, except in MP when I had to take off near a harbor. When I looked that way my FPS dropped to 10. I thought it was because of the city, but as I flew closer I realized that looking at the city is no FPS hit. It was when I looked at the reflections of the mountains in the water. At least I think so, because as soon as I flew closer and they were not visible anymore, the performance was OK. Anyone else experienced this?

 

Thx,

Greg