Hi,
Your query is quite a complex one.Break it down into small parts.
1)The inner join should not contain more than 2 tables.Otherwise the Query performance will be seriously affected.
2)Include as many conditions as possible in the Where clause and the order of the fields in the Where clause should be the same as in the Database Table.
3)Check whether indexes are created for fields accessed in the Where clause.
4)Use the Statement DELETE ADJACENT DUPLICATES to remove duplicate entries from the table.
5)Avoid INTO CORRESPONDING FIELDS OF TABLE <Table_Name>.Instead use INTO TABLE <Table_Name>.
6)If your performing FOR ALL ENTRIES then check if the internal table is empty or not i.e. Check the condition IS NOT INITIAL then perform select using FOR ALL ENTRIES.
7)Also check IS INITIAL condition and SY-SUBRC values for blank values.