I think a number of us have had the same issue on systems with a lot of items and inventory history. We had one at 45 hours and handled it by copying the active company to an inactive company and purging active inventory history down to about 7 years. That got us down to about 24 hours. After the active company went live, we migrated and converted the inactive company to allow lookup of really old stuff. They aren't sure they will ever need it but it's there if they do.