(Il-2) Lower proformance on pacific campaings?

Ive knoticed that I'm getting noticably lower proformance on pacific maps then europe maps, I dunno if its the ships, water, or even my crappy processor or what, but the 4x time acceleration is slower then 8x on europe maps like when I work on my german/soviet campaigns. Also depending on whats on screen at the moment it can sometimes get choppy without any time acceleration. Is there any fix/workaround for this? Setting lower ingame-graphics settings doesnt't seem to do anything noticable.