Guys, I was doing some tests here and I found something odd.
I made a backup of my controls and graphics settings(Saved Games - DCS - Config - Input) and started DCS for a Quick Mission with the Su-33. I didn´t set anything, only the same graphics settings, the axis and FF settings are from the game.
The Su-33 seems to be not affected for the FPS drops, when in flight over the sea, only when I started to flight above the cities, obviously my FPS drops from 50 to 45/40 but it was a very smoothly to fly with this FPS, but then, I picked the A10A on the Quick Mission but the FPS drops started when I made a hard turn after the FF turned it on.
Try yourself and give your feedback to ED, let´s help them to solve this problem for us.