Continuous calls to Ajax Modal Popup makes page slow

Question

I am using Ajax modal popup on a page. This can be called n number of time. Steps are:
1. User opens the Modal popup.
2. Do some server things.
3. Fire OK server event. This will also hide() the modal popup.

After repeting these steps almost 5 - 10 times, it makes page very slow.

I have also called dispose() method of modal popup while hiding(). But it still makes page very slow. Page has a scrollbar, while scrolling, I can identifies how much page gets slower.

Once I refresh the page, then it becomes fine.