I don't know if it works in this case, but a trick that works in most Windows programs is to simply grab the scrollbar and move it a little. That seems to block any screen updates to the list except scrolling until you release it. The rest of the program still churns on happily in the background, though.
It is not a trick. It is implemented this way. If the scroll thumb is at the bottom then it will scroll automatically. Otherwise the scroll position will be kept (until the queue is full).