Find the problematic SQL ID to investigate, then execute:
col report_id new_v report_id select * from ( select * from DBA_HIST_REPORTS where key1 = '&&sql_id' and COMPONENT_NAME = 'sqlmonitor' order by generation_time desc ) where rownum = 1;
This will give you the most recent execution, but you may want to use different criteria. Next, generate a plan statistics report in text format:
SELECT DBMS_AUTO_REPORT.REPORT_REPOSITORY_DETAIL( RID => &&report_id , TYPE => 'text') FROM dual;
This report contains all sorts of useful information to help pin down the performance bottleneck.