I don't know the answer to this or if it makes much difference, but I will throw it out here and see if someone can hash it out.
What would be the difference in "lag time" between these two scenarios:
1. You place an enemy in your level and his AI script is looping on a "plrdistwithin" line to continue his actions, or
2. You place a zone to spawn the enemy and it's AI script is looping on a "plrwithinzone" to continue it's actions and spawn the enemy.
If it is the scripts that cause excess lag time as some say, then I can see no difference between the two as far as "lag time" is concerned. There are other uses, of course, such as an enemy appearing behind the player, etc....
Best.
BTW: It's a good tut. Nice to see it visually done. I have done this before as well and never saw the shadow either.
The forum provides a means to hide our true identity. Too bad we always screw up and let it be seen.