NPCs in city-less worlds really slow the game down

[Coolthulhu]

As reported in http://smf.cataclysmdda.com/index.php?topic=15122.0

"Wild" NPCs look for shops and houses to loot. When those don't exist, they fail to find something to do, meaning that their next action will be looking for something to do (ie. scanning for shops and houses to loot).
The radius for this scan is whooping 5 overmap widths - (180*5)^2=810000 tiles to check. And the per-terrain check is a string comparison.

[Kole6738]

Could we drop it down to 1 overmap width as a stopgap measure? That's still quite a large area to scan (32400) to allow AI behavior and would cut down processing by a significant factor.

[ZhilkinSerg]

Could we drop it down to 1 overmap width as a stopgap measure?

It will decrease slowdonw, but won't really help as there are still no shops and houses in 1 overmap radius.

I suggest npcs should traverse field overmap terrain in worlds with CITY_SIZE = 0.