Parent window is hard to be navigated away

[Mark]

Hi guys,

I have two windows, one is the parent and the other is the child which gets
pop-upped by the parent window javascript code. When the child is loading
heavy content, in my case is a heavy report (by reportviewer control) the
parent page takes very very long time to be navigated away(by clicking a
hyper link on the page).

What is probably causing this issue? Thanks!

Mark