PHP - преобразование файла SQL CE в SQLITE происходит медленно

           /**
             * ARBalances
             */
            $file_db->exec("CREATE TABLE IF NOT EXISTS ARBalances (
                    _id INTEGER PRIMARY KEY AUTOINCREMENT,
                    CustomerCode NVARCHAR(10),
                    BillingDate TEXT,
                    Balance DECIMAL(15,2),
                    SalesId NVARCHAR(30),
                    Amount DECIMAL(18,2),
                    Payment DECIMAL(18,2))");
          
          
          /**
             * Insert Data to db file. Select ARBalances from SDF file
             */
            $sdf->execute("SELECT * FROM ARBalances");

            $this->data_array = [
              'customer_code' => NULL,
              'billing_date' => NULL,
              'balance' => NULL,
              'sales_id' => NULL,
              'amount' => NULL,
              'payment' => NULL,
            ];

            $ar_balances = [];

            while (!$sdf->eof()) {

              $ar_balances[$sdf->fieldvalue('SalesId')] = $this->data_array;
              $ar_balances[$sdf->fieldvalue('SalesId')]['customer_code'] = $sdf->fieldvalue('CustomerCode');

              $date = str_replace('/', '-', $sdf->fieldvalue('BillingDate'));
              $date = new DateTime($date);
              $billing_date = strtotime($date->format('Y-m-d H:i:s'));
              $billing_date = (int)$billing_date * 1000;

              $ar_balances[$sdf->fieldvalue('SalesId')]['billing_date'] = $billing_date;
              $ar_balances[$sdf->fieldvalue('SalesId')]['balance'] = (float)$sdf->fieldvalue('Balance');
              $ar_balances[$sdf->fieldvalue('SalesId')]['sales_id'] = (string)$sdf->fieldvalue('SalesId');
              $ar_balances[$sdf->fieldvalue('SalesId')]['amount'] = (float)$sdf->fieldvalue('Amount');
              $ar_balances[$sdf->fieldvalue('SalesId')]['payment'] = (float)$sdf->fieldvalue('Payment');

              $sdf->movenext();
            }

            $insert = "INSERT INTO ARBalances(CustomerCode, BillingDate, Balance, SalesId, Amount, Payment)
                      VALUES (:customer_code, :billing_date, :balance, :sales_id, :amount, :payment)";

            $stmt = $file_db->prepare($insert);

            $stmt->bindParam(':customer_code', $customer_code);
            $stmt->bindParam(':billing_date', $billing_date);
            $stmt->bindParam(':balance', $balance);
            $stmt->bindParam(':sales_id', $sales_id);
            $stmt->bindParam(':amount', $amount);
            $stmt->bindParam(':payment', $payment);

            foreach ($ar_balances as $value) {
              $customer_code = $value['customer_code'];
              $billing_date = $value['billing_date'];
              $balance = $value['balance'];
              $sales_id = $value['sales_id'];
              $amount = $value['amount'];
              $payment = $value['payment'];
              $stmt->execute();
            }