Flash Ball example slow in some cases

The ball example that I did is slow in IE7 on my windows vista.
When I open the swf in the browser on IE and on Safari it is also slow.
In Firefox,opera,safari it is fast when embedded in a page.
When I open the swf in the browser on firefox 2, it starts fast and then goes slow.
In opera when It is embedded in a page it is fast, and when I open it in a browser it is also fast!