I would like to remove some of the npcs (commoners and nobles) just so there isn't as much trouble on my computer. In fact I only play Mca for all the companions XD. I've tried deleting them through the construction set but I don't think i'm doing it right..
Basically MCA works by spawning NPCs through the Levelled Creature lists. It adds markers to the game areas where they spawn (the ninja monkeys in the CS). There are a few ways to reduce how many NPCs will spawn.
1. Increase the number in the 'Chance None' box on all the lists (this box is the % chance that nothing will spawn when the marker is activated).
2. Remove some or all of the markers from the world by hand
3. Delete some of the levelled lists entirely.
Number 1 is the easiest and most customizable way. If you're really just playing it for the companions then set every list to 100 'Chance None', or just the nobles/commoners if you still want hostile npcs to spawn. If you want all npcs to spawn but not nearly so often, try putting 80 in the 'Chance None' box.