[Doolar]

don't know if this helps but on a rare occasion, I notice a creaking sound that seems to be stuck in a repeating loop if I surface the boat at a high time compressions. To fix this I do a quick dive to 30meters then resurface. It never happens now that I don't surface at more then 8x or 16x. Which is good practice anyway.

as for low frame rates in the map screen. I use to leave all my X's and circles and lines drawn on the map for the entire patrol. After awhile in the map screen my mouse curser was slow to react and jumpy. Someone here on the forum suggested that I remove my old and useless map markings from time to time and since then, I don't experience that either.