generic delete query

Oracle EE 11.2.0.2 on rhel 5.7

Can someone tell me if the following query can be improved? It takes several minutes to run.

Thanks.

delete from cle.SAKAI_REALM_RL_FN SRRF

      where SRRF.REALM_KEY in

                (select R.REALM_KEY from cle.SAKAI_SITE S, cle.SAKAI_SITE_PROPERTY SP, cle.SAKAI_REALM R

                     where SP.NAME='term_eid'

                        and CAST (SP.VALUE as VARCHAR(10)) ='2012F'

                        and SP.SITE_ID=S.SITE_ID

                        and S.TYPE='course'

                        and R.REALM_ID like '/site/'||S.SITE_ID)

        and SRRF.ROLE_KEY in

                (select ROLE_KEY from cle.SAKAI_REALM_ROLE SRR where