Are you sure your game didn't accidentally switch to Realistic Game Mode?
Please double check your Options menu.
Positive. Checked multiple times, even changed them just to be sure, as it is right now, Arcade and Realistic are working in exactly the same fashion. With the exception that I can fast travel while in Arcade mode. Its not a big deal, as I suspect I'm one of a few people who play in arcade, but its noticeable enough to me. I've gone from the mid 20's down to around 14 and below at most times. I sail into the wind and I don't really move at all.
Now, this is with the 4.1 Beta WIP September 13th build. However, I did apply three fixes from the forums.
1. Boarding AI.
2. Your fix for the Sao Gorge trader, as posted by another user to his files.
3. The guard fix by levis.
*Edit 2 * I removed these files and returned the originals for no change whatsoever. It seems the fixes had nothing to do with the problems.
Upon further inspection. I can further differentiate between arcade and realism by the way the ship turns. I started switching between realistic and arcade. I then tried turning the ship at different angles and recording speeds.
I had 14 wind power against my sails, and in realism it was harder to turn, and my sloop went 5.4
I then switched from realistic to arcade.
I had 14 wind power against my sails, and in arcade it was easier to turn and my sloop went 7.6
Im beginning to think that the July 28th arcade mode was more pronounced, or I simply did something differently. Maybe I had higher sailing skill and a better officer? Maybe campaign has different winds? Ill need to test various things.
@Grey Roger
Here's the thing. I don't HAVE any other saves or profiles. I deleted them all during the move to september 13th build. Just to be sure I double checked the SAVES folder in my POTC install. There is nothing in any of those folders but the Freeplay folder with my saves from yesterday.