I'm not sure at all what is causing this but theirs about a 50/50 chance of a ragdoll crashing the game when it hits the ground. This only applies to NPC's however. And if the ragdoll doesn't crash the game, it will just vanish causing massive frame drops. I don't know if this is a compatibility issue or whatever but I can't play with Fedhoria now because of this game breaking bug

Edit: It's caused by setting "die time" to absolute zero. I'm still keeping this up as it should be fixed