Can I use clear interval to speed this up? (if so not sure how to use properly)

Hello,
I am using some code that was posted in this thread: http://www.kirupa.com/forum/showthread.php?t=73072&highlight=vanish
(it was created by virusescu)

Anyway, I think I need to use a clear interval in here because it runs great if used once, but if I try to repeat the code at a later time everything runs slow and lags. I am going to try and get by without posting the fla, but I will give a link to the page I am using the swf on and here is the code. Please let me know if I do need to post the fla. (this code is used in frame 30 and then again in frame 200, which is the point where it slows everything down.

for (a = 0; a < 20; a++)
{
for (b = 0; b < 10; b++)
{
_root.attachMovie(“dot”, “x” + a + “y” + b, z++);
_root[“x” + a + “y” + b]._x = 20 * a;
_root[“x” + a + “y” + b]._y = 20 * b;
}
}
a =0;
b =0;
function vanish()
{
for (b = 0; b<15;b++ ) {
_root[“x” + a + “y” + b].play();
}
a++;
}
this.onEnterFrame = function() {
asd = setInterval(_root.vanish,30);
}

SWF can be viewed here:

http://www.cbservices.org/cbs/test/msi/index-new.html