ActionScript 3.0 :: How To Get MovieClip To Face Mouse

I'm making a top down shooter and I'm encountering some interesting code lag with the function I'm using to make the player face the mouse.

Code:
//The function is called through a ENTER_FRAME listener.
//mX & mY are the current position of the mouse.
public function facePoint(mX, mY){
if(this.visible){
this.rotation = (-Math.atan2((this.x - mX),(this.y - mY))) * 180 / Math.PI;
}}

If I hold down two movement keys and then spin the mouse around the character really fast, it builds up some kind of buffer that sends the character out of control for a few seconds, even after you've released the keys. Just discovered that reducing the quality to low removes the issue entirely... so its a graphics problem. How to avoid this?