insert to oracle DB is slow- JDBC

Question

I am looping over a queue of 1 million XMLS and I parse every xml and insert its values into 5 arraylist. each arraylist load data into a table in Oracle. After parsing 1000 XMLs I load the data into the DB while the data volume is around 500k - 1M records for each table. the problem after every load the insertion time extend and after 3-4 loads the program barly moves. questions 1. if talking about performance what is better: open many DB connections and insert small amount of data or open few connection with big amount of data? 2. please help to reduce the insertion time.

example for 1 of my DB load code

//Party
        sql="INSERT INTO  CRMAS_ODS_RAW_DATA.PARTY_TMP(BATCH_ID, SOURCE_SYSTEM, UPDATE_DATE, PARTY_KEY, TCCID, LEI_ID, NATIONAL_ID, OFF_SET)  VALUES(?,?,?,?,?,?,?,?)";
        ps = con.prepareStatement(sql);
        timestamp = new Timestamp(System.currentTimeMillis());
        count = 0;
        con.setAutoCommit(false);
        for(Party par : al4) 
        {
            // get batchid
            ps.setInt(1,par.getA1());
            // get SOURCE_SYSTEM
            ps.setString(2,par.getA2());
            // get UPDATE_DATE
            ps.setTimestamp(3,timestamp);
            // get party_key
            ps.setString(4,par.getParty_key());
            // get TCCID
            ps.setInt(5,par.getA4());
            // LEI_ID
            ps.setString(6,par.getLEI());
            // NATIONAL_ID
            ps.setString(7,par.getNationalId());
            // OFF_SET
            ps.setLong(8,par.getOffset());

            ps.addBatch();
            if(++count % Batch_party == 0) {

                ps.executeBatch();
                timestamp = new Timestamp(System.currentTimeMillis());
            }
        }
        con.setAutoCommit(false);
        ps.executeBatch(); // insert remaining records
        con.commit();