I believe, there is no option cascade constraints in Truncate table.
Do this excercise.

1. spool trunc.sql
2. select 'truncate table ' || owner || '.' || table_name || ';' from sys.all_all_tables where owner in ('PERFSTAT');

Caution: The above will truncate all the tables owned by PERFSTAT.

2. spool off
3. Edit the trunc.sql and remove the unwanted scripts.
4. Then, finally run the trunc.sql

Hope this will work.