Illagers Don't Drop Aggro

I've noticed that any illager type mob doesn't not seem to ever drop aggro, no matter how far you move away. This isn't usually a problem, enough maneuvering illagers can dealt with. However, there is a problem with Evokers, as they will keep spawning Vex's and if there are to many, the entire area will be nearly impossible to be in. Please fixe this as i have been chased away from so many woodland cabin structures because of this.