I thought it was just something us owners of lowly graphics cards experienced, but an owner of a shiny nVidia 8800GT, said no, it came with being in port. It's the increase in objects your computer has to keep track of at one time that the slowdown occurs. The most congested place is a harbor, so that is where we see the slowdowns. You can help it a little, and this applies to fleet boats and U-Boats.
Turn off your radar. That will cut the number of contacts greatly. Reduce time compression. There's nothing like the resounding crash of entering a harbor at 2048x with your controls frozen and that look of horror on your face won't save you!:rotfl:Other than that, slowdowns there are a fact of live. That's why originally harbors were so empty. The slowdowns are due to populating the harbors in response to players' complaints.
Must be hell to be a developer.

Hat's off to all of them!