Executing the same query multiple times gets slow

I have a complex query that returns about 5,000 records and only a few columns.  If I run it in psql repeatedly, it's always fast.  If I run it through JDBC it runs fast at first but then it gets real slow (> 50 seconds).  I can't understand why it would get slow after 30 runs of the exact same query.

I am running:

Linux / 64GB RAM

PostgreSQL 15.1

postgresql-42.5.4.jar

I am using a prepared statement but a new one each time even though it is the same query (there are reasons for this).

I found the line that's having the delay is:  pstat.executeQuery();

where:  PreparedStatement pstat;

Sure appreciate any pointers!

Thanks.

Blake