Index: umc/python/udm/udm_ldap.py
===================================================================
--- umc/python/udm/udm_ldap.py	(Revision 40329)
+++ umc/python/udm/udm_ldap.py	(Arbeitskopie)
@@ -1068,28 +1068,43 @@
 		def map_choices( obj_list ):
 			result = []
 			for obj in obj_list:
-				obj.open()
-
+				# first try it without obj.open() (expensive)
+				key = label = None
 				if syn.key == 'dn':
 					key = obj.dn
-				else:
+				if syn.label == 'dn':
+					label = obj.dn
+				if key is None:
 					try:
 						key = syn.key % obj.info
 					except KeyError:
-						# ignore the entry as the key is important for a selection, there
-						# is no sensible fallback for the key (Bug #26994)
-						continue
-				if syn.label is None:
-					label = udm_objects.description( obj )
-				elif syn.label == 'dn':
-					label = obj.dn
-				else:
+						# key is not yet in obj.info -> obj.open()!
+						pass
+				if label is None and syn.label is not None:
 					try:
 						label = syn.label % obj.info
 					except KeyError:
-						# fallback to the default description as this is just what displayed
-						# to the user (Bug #26994)
-						label = udm_objects.description( obj )
+						# key is not yet in obj.info -> obj.open()!
+						pass
+				if key is None or label is None:
+					obj.open()
+					if key is None:
+						try:
+							key = syn.key % obj.info
+						except KeyError:
+							# ignore the entry as the key is important for a selection, there
+							# is no sensible fallback for the key (Bug #26994)
+							continue
+					if label is None:
+						if syn.label is None:
+							label = udm_objects.description( obj )
+						else:
+							try:
+								label = syn.label % obj.info
+							except KeyError:
+								# fallback to the default description as this is just what displayed
+								# to the user (Bug #26994)
+								label = udm_objects.description( obj )
 
 				result.append( (key, label) )
 			return result