It seems that performance problems with lots of items are gone now.
Great job there Kevin (and possibly others).
To test it, I set item spawn to 10 and monster spawn to 50 (max values) and teleported into the center tile of a mall. It took a long while to load (few seconds), but after I debug killed the zombies, there was only a minor slowdown. Item listing showed 800 items (despite limited vision), many of which were active (zombie corpses, maybe food too).
The second test was spawning and dropping 10k rags. Dropping them took ages, after that it didn’t cause any noticeable slowdown.