I've detailed the issue in reddit but I figured that I should bring the issue to here from the reddit.
https://www.reddit.com/r/feedthebeast/comments/1biexc5/comment/kvpzje3/?utm_source=share&utm_medium=web2x&context=3

"Can spawn on mobs, making nearby animals hostile to you" I was wondering why I was having an issue with over spawning animals in underground cave that lagged my single player world (to the point that I had to yeet the save of my single player world) until i disable your mod. Is there a way to disable that?

Edit: I went to butchercraft-common toml and tried to set hoodChanceMultiplier from 1.0 to 0.1 to make them rare and set armyHoodChanceMultiplier from 0.1 to 0 to prevent them from spawning animals. For some reason, they were reset back to default.

Suggestion: Have undead only temporarily spawn mobs on a sight of a players and then despawn the mobs after a period of time rather than passive spawning them and keep them spawned. That way, it won't over spawn & clog up the underground caves. Best of both world!