Add patch for issue9797.

issue9797.diff

@@ -0,0 +1,33 @@
+index ac29d17..2b240c1 100644
+--- a/trytond/trytond/modules/account_payment_sepa/payment.py
++++ b/trytond/trytond/modules/account_payment_sepa/payment.py
+@@ -190,18 +190,23 @@ class Group(metaclass=PoolMeta):
+         Payment = pool.get('account.payment')
+         if self.kind == 'receivable':
+             mandates = Payment.get_sepa_mandates(self.payments)
++            sequence_types = {}
+             for payment, mandate in zip(self.payments, mandates):
+                 if not mandate:
+                     raise ProcessError(
+                         gettext('account_payment_sepa'
+                             '.msg_payment_process_no_mandate',
+                             payment=payment.rec_name))
+-                # Write one by one because mandate.sequence_type must be
+-                # recomputed each time
+-                Payment.write([payment], {
+-                        'sepa_mandate': mandate,
+-                        'sepa_mandate_sequence_type': mandate.sequence_type,
+-                        })
++                sequence_type = sequence_types.get(mandate)
++                if not sequence_type:
++                    sequence_type = mandate.sequence_type
++                    if sequence_type == 'FRST':
++                        sequence_types[mandate] = 'RCUR'
++                    else:
++                        sequence_types[mandate] = sequence_type
++                payment.sepa_mandate = mandate
++                payment.sepa_mandate_sequence_type = sequence_type
++            Payment.save(self.payments)
+         else:
+             for payment in self.payments:
+                 if not payment.sepa_bank_account_number:

series

@@ -39,3 +39,5 @@ lazy_loading.diff # [trytond] https://discuss.tryton.org/t/should-create-uid-wri
 issue9103.diff # [trytond] User-defined reports for custom template extensions
 
 issue9616.diff # [analytic_invoice] Analytic move is not created when closing an asset
+
+issue9797.diff # [account_payment_sepa] Slowness processing sepa