[MaddogK]

In a word- DOCK.
I've been experiencing more and more save game CTD's than ever as well as time compression limits, and they get worse the more tonnage I've sunk. I recently lost 126k tons when a save refused to reload the following day so I had to replay the entire 6 hour ordeal from a previous save and dock (end patrol) to claim the sunk ships.

Since the new patrol started the game loads almost instantly again, and I'm no longer limited to a time compression value of 512.