Well, I'm nearly at the end of the game. After returning from Dead City I visited Peregon, to sell itmes. And when I rest there to renew merchants I've noticed that game slowed down a lot. The more I rest the more it choked, to the point it became unplayable. It was directly related to merchants changing. i've noticed that middle merchant has no guards. And I found them all, spawning new guards every time new merchant shows up. They are spawn on each other, and game goes crazy. It's at some point too many objects on the same spot. Please see the screenshot attached.

[EDIT 1] Reloading the game doesn't work. Issue remains.

Update: I even reloaded the game to Dead City and upon returning the issue remains. I also found the guilty merchant, when he shows up, extra guard is added on railtracks. Anyone else having this bug?

I have the same bug and it didn't resolve itself. The sequence of events was that I robbed a caravan, I fought all of the resulting mercenaries (for some reason the mercenary groups all appeared one after another in reverse order of difficulty after the initial "you have been trapped by mercenaries" epic nighttime fight event with the armored vehicle).

The next time I went to Peregon to sell items, the big merchant caravan was there, but it no longer had any guards (just the merchant). The small caravan was also there but it now had 5 guards rather than 3.

After I rested once, the big caravan merchant's outfit started to flip quickly through all of the different merchant appearances (bald guy, big hat guy, small hat guy, etc, about three changes per second), so I left Peregon to see if it would clear up.

When I came back to Peregon, the big caravan merchant was still alone, he had stopped flipping through his appearances, the small caravan still had two extra guards, and the framerate in Peregon was about 3 FPS and that has never again improved in my playthrough. This is Mac 1.085 OSX fix version.

EDIT: when I peek at the contents of Progress/Harbor_1.dat, there are 418 unique "character":"Karavan.Guard_3" entries, and there are approximately the same amount of them in Save_0_v10.as which is a save file in which I've verified I see this issue.

EDIT 2: I feel obligated to say that I'm fairly impressed that the game is almost still playable with over 400 invisible characters and their state, faction and inventory added to Peregon :D.