You appear to be leaving your JDBC statements open. Until the connection is closed, all of these statements remain in memory in the JDBC driver. As you appear to keep the connection open; this causes a small but constant memory leak for every query executed.

You do not need to close result sets, as closing the statement will automatically close a result set.

done

Nice. Do you maintain a lot of other plugins with this issue?

SimpleClans should have the same problem.