Console messages are not as bad as you make them sound. For years the game has logged plenty of console messages as you play. It takes dozens/hundreds in a short time period to start lagging unless you have some weird issue with it writing to the file.
Now the code that is logging the message might be running slow, but that is not from the message itself.
If they don't take any damage then it is probably a bug, but I would not want them taking much damage even if we fix it, because people would make low resources corridors full of campfires to kill zombies. Yes we should fix it, but it would be way down the list of things we need to worry about.