diff --git a/tailbone_corepos/views/corepos/master.py b/tailbone_corepos/views/corepos/master.py
index e59d1b6..3d47ceb 100644
--- a/tailbone_corepos/views/corepos/master.py
+++ b/tailbone_corepos/views/corepos/master.py
@@ -66,6 +66,10 @@ class CoreOfficeMasterView(MasterView):
 
         return CoreOfficeSession
 
+    def results_xlsx_session(self):
+        from corepos.db.office_op import Session as CoreSession
+        return CoreSession()
+
     def render_local_date(self, obj, field):
         value = getattr(obj, field)
         if not value:
diff --git a/tailbone_corepos/views/corepos/products.py b/tailbone_corepos/views/corepos/products.py
index 6c53e21..2cbee3d 100644
--- a/tailbone_corepos/views/corepos/products.py
+++ b/tailbone_corepos/views/corepos/products.py
@@ -143,16 +143,29 @@ class ProductView(CoreOfficeMasterView):
 
     def get_xlsx_fields(self):
         fields = super(ProductView, self).get_xlsx_fields()
+
+        # add our extra field
         fields.append('superdepartment_number')
+
+        # but also, go ahead and cache the superdept mapping, for performance
+        mapping = {}
+        super_departments = self.Session.query(corepos.SuperDepartment).all()
+        for superdept in super_departments:
+            if superdept.child_id in mapping:
+                if superdept.parent_id < mapping[superdept.child_id]:
+                    mapping[superdept.child_id] = superdept.parent_id
+            else:
+                mapping[superdept.child_id] = superdept.parent_id
+        self.supermap = mapping
+
         return fields
 
     def get_xlsx_row(self, product, fields):
         row = super(ProductView, self).get_xlsx_row(product, fields)
 
         row['superdepartment_number'] = None
-        dept = product.department
-        if dept and dept._super_parents:
-            row['superdepartment_number'] = dept._super_parents[0].parent_id
+        if product.department_number in self.supermap:
+            row['superdepartment_number'] = self.supermap[product.department_number]
 
         return row