Mirando lo que dijiste que no puedes crear índices. Espero que la consulta esté haciendo un escaneo completo de la tabla en la tabla. Intente con una sugerencia paralela.
select /*+ full(so) parallel(so, 4) */ 0 test_section, count(1) count, 'DD' test_section_value
from svc_order so, event e
where so.svc_order_id = e.svc_order_id
and so.entered_date >= to_date('01/01/2012', 'MM/DD/YYYY')
and e.event_type = 230 and e.event_level = 'O'
and e.current_sched_date between
to_date( '09/01/2010 00:00:00', 'MM/DD/YYYY HH24:MI:SS')
and to_date('09/29/2013 23:59:59', 'MM/DD/YYYY HH24:MI:SS')
and (((so.sots_ta = 'N') and (so.action_type = 0))
or ((so.sots_ta is null) and (so.action_type = 0))
or ((so.sots_ta = 'N') and (so.action_type is null)))
and so.company_code = 'LL'
