Performance - Totally collapsed grid with 70000 rows is incredibly slow

I have a pivot grid that is bound to a dynamically populated IList which is populated with data entities generated through an ORM tool. The tables the data is being pulled from have a large amount of fields(67) 16 of which default to be in the row area while the others are in the Customization Window. With a little waiting the PivotGrid renders with all the appropriate data however, I would like to have the pivot grid to have all of its row fields collapsed when it starts up, so the user doesn't have a data overload and can have a high level view of the data when they start.
I was able to accomplish this by iterating through the PivotGrid's Fields, and when the field was a row, I called CollapseAll() on it. This worked just fine when the number of fields in the row area was smaller. But with the current table this is not the case, the PivotGrid renders initially just fine, with all of its rows collapsed, however when I attempt to expand the first row, the loading panel pops up and doesn't go away. I left it running for over 3 hours without any results.
If I do not collapse all the row fields the grid works just fine, if a bit sluggishly, but if I start from the right most row field and collapse all, working my way towards the left most row field, after collapsing the 4th or 5th row it locks up as noted before.

Here is a project that replicates the error I am getting.

Thanks,
Greg