Mc chasing mouse

how to make mc chasing mouse in a smoother way?
coz i did mine and it was not smooth enough
here is the script applied

stop();
speed = 18;
function moveChaser() {
if (chaser._x<_root._xmouse-speed) {
chaser._x += speed;
} else if (chaser._x>_root._xmouse+speed) {
chaser._x -= speed;
}
if (chaser._y<_root._ymouse-speed) {
chaser._y += speed;
} else if (chaser._y>_root._ymouse+speed) {
chaser._y -= speed;
}
};

if i increase the speed it will moving so fast that will not any movement… if the speed slow is decreased the speed will be slow… either way… i want my mc that following mouse pointer is smooth…
so how can i fix this problem? thanks i advance