How can I optimize this query - Mailing list pgsql-sql

I have the following query

UPDATE accumulator1 SET accumulator1.status = "User Excluded"
WHERE accumulator1.name NOT IN
(SELECT DISTINCT accumulator1.nameFROM accumulator1, diaaffectedstmtsWHERE diaaffectedstmts.stmt like '*'+
accumulator1.name+'*' and 
diaaffectedstmts.xref_type <>  "D");

How can I optimize this query?

Thanks
Jain