Mouse cursors get choppy

In my Flash movie, when the user moves the mouse the alpha of a movie clip changes. At the same time I have changed the mouse cursor. The problem is that when the the alpha is being adjusted the cursor movements get really choppy. Here’s the code that I have on the movie’s first frame:
function cursorUpdate () {
_root.cursor._x = _xmouse;
_root.cursor._y = _ymouse;
updateAfterEvent(mouseMove);
}

And here’s the code on the cursor MC:
onClipEvent (load) {
Mouse.hide();
this.swapDepths(100);
}
onClipEvent (mouseMove) {
_root.cursorUpdate();
}

If anyone’s got any suggestions, do tell! Thanks.

its just that Flash cant keep up. You will either need to optimize or just deal with it :-\