Query fluctuates .... Strange strange .....

PG 8.3.7 on HP 11.31.
Very strong Server with lots of memory.
A query runs that inserts 40K records takes 1 second when run from psql.
It takes 20 minutes!!  And  100% CPU !!   when called from a standalone JDBC program.
No other users are running !!!

The problematic query:

2013-01-02 15:00:38.008 ISTLOG:  duration: 1207547.589 ms  execute <unnamed>: insert into CMR_IOALOG_2 select * from
CMR_IOALOG_PRE where ORDERNO in (select ORDERNO from CMR_AJF_PRE) or ORDERNO=0