po30 select taking taking over 3 minutes for user

Does anyone have any ideas on how to trouble-shot a (select) drop down performance problem?  A user reported that it is taking 3 1/2 minutes for the select on the PO field to pull a list of open receiving by item on the po30 screen.  It is slow on LID and portal.  I can recreate the issue but for the user it is twice as slow.  I was going to have the dba take a look at perhaps rebuilding the index the select uses (PLISET6).