Executing the same query multiple times gets slow

Greetings,

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