diff -r 3681a54fda0a trytond/trytond/modules/account_invoice/invoice.py
--- a/trytond/trytond/modules/account_invoice/invoice.py	Tue Jul 07 16:46:50 2015 +0200
+++ b/trytond/trytond/modules/account_invoice/invoice.py	Tue Jul 07 17:12:14 2015 +0200
@@ -852,7 +852,7 @@
             if line.type != 'line':
                 continue
             with Transaction().set_context(**context):
-                tax_list = Tax.compute(Tax.browse(line.taxes),
+                tax_list = Tax.compute(line.taxes,
                     line.unit_price, line.quantity,
                     date=self.accounting_date or self.invoice_date)
             for tax in tax_list:
@@ -944,33 +944,35 @@
         '''
         Return move line
         '''
-        Currency = Pool().get('currency.currency')
-        res = {}
+        pool = Pool()
+        Currency = pool.get('currency.currency')
+        MoveLine = pool.get('account.move.line')
+        line = MoveLine()
         if self.currency.id != self.company.currency.id:
             with Transaction().set_context(date=self.currency_date):
-                res['amount_second_currency'] = Currency.compute(
+                line.amount_second_currency = Currency.compute(
                     self.company.currency, amount, self.currency)
-            res['amount_second_currency'] = abs(res['amount_second_currency'])
-            res['second_currency'] = self.currency.id
+            line.amount_second_currency = abs(line.amount_second_currency)
+            line.second_currency = self.currency.id
         else:
-            res['amount_second_currency'] = None
-            res['second_currency'] = None
+            line.amount_second_currency = None
+            line.second_currency = None
         if amount >= Decimal('0.0'):
-            res['debit'] = Decimal('0.0')
-            res['credit'] = amount
+            line.debit = Decimal('0.0')
+            line.credit = amount
         else:
-            res['debit'] = - amount
-            res['credit'] = Decimal('0.0')
-        res['account'] = self.account.id
+            line.debit = - amount
+            line.credit = Decimal('0.0')
+        line.account = self.account.id
         if self.account.party_required:
-            res['party'] = self.party.id
-        res['maturity_date'] = date
-        res['description'] = self.description
-        return res
+            line.party = self.party.id
+        line.maturity_date = date
+        line.description = self.description
+        return line

-    def create_move(self):
+    def get_move(self):
         '''
-        Create account move for the invoice and return the created move
+        Compute account move for the invoice and return the created move
         '''
         pool = Pool()
         Move = pool.get('account.move')
@@ -986,10 +988,10 @@
         total = Decimal('0.0')
         total_currency = Decimal('0.0')
         for line in move_lines:
-            total += line['debit'] - line['credit']
-            if line['amount_second_currency']:
-                total_currency += line['amount_second_currency'].copy_sign(
-                    line['debit'] - line['credit'])
+            total += line.debit - line.credit
+            if line.amount_second_currency:
+                total_currency += line.amount_second_currency.copy_sign(
+                    line.debit - line.credit)

         term_lines = self.payment_term.compute(total, self.company.currency,
             self.invoice_date)
@@ -997,28 +999,23 @@
         if not term_lines:
             term_lines = [(Date.today(), total)]
         for date, amount in term_lines:
-            val = self._get_move_line(date, amount)
-            if val['amount_second_currency']:
-                remainder_total_currency += val['amount_second_currency']
-            move_lines.append(val)
+            line = self._get_move_line(date, amount)
+            if line.amount_second_currency:
+                remainder_total_currency += line.amount_second_currency
+            move_lines.append(line)
         if not self.currency.is_zero(remainder_total_currency):
-            move_lines[-1]['amount_second_currency'] -= \
+            move_lines[-1].amount_second_currency -= \
                 remainder_total_currency
-
         accounting_date = self.accounting_date or self.invoice_date
         period_id = Period.find(self.company.id, date=accounting_date)

-        move, = Move.create([{
-                    'journal': self.journal.id,
-                    'period': period_id,
-                    'date': accounting_date,
-                    'origin': str(self),
-                    'company': self.company.id,
-                    'lines': [('create', move_lines)],
-                    }])
-        self.write([self], {
-                'move': move.id,
-                })
+        move = Move()
+        move.journal = self.journal
+        move.period = period_id
+        move.date = accounting_date
+        move.origin = self
+        move.company = self.company
+        move.lines = move_lines
         return move

     def set_number(self):
@@ -1050,11 +1047,10 @@
         with Transaction().set_context(
                 date=self.invoice_date or Date.today()):
             number = Sequence.get_id(sequence.id)
-            vals = {'number': number}
+            self.number = number
             if (not self.invoice_date
                     and self.type in ('out_invoice', 'out_credit_note')):
-                vals['invoice_date'] = Transaction().context['date']
-        self.write([self], vals)
+                self.invoice_date = Transaction().context['date']

     @classmethod
     def check_modify(cls, invoices):
@@ -1106,7 +1102,7 @@
             all_invoices += invoices
         update_tax = [i for i in all_invoices if i.state == 'draft']
         super(Invoice, cls).write(*args)
-        if update_tax:
+        if update_tax and not Transaction().context.get('skip_update_taxes'):
             cls.update_taxes(update_tax)

     @classmethod
@@ -1337,18 +1333,16 @@
         '''
         MoveLine = Pool().get('account.move.line')

-        new_invoices = []
-        for invoice in invoices:
-            new_invoice, = cls.create([invoice._credit()])
-            new_invoices.append(new_invoice)
-            if refund:
-                cls.post([new_invoice])
+        new_invoices = cls.create([i._credit() for i in invoices])
+        cls.update_taxes(new_invoices)
+        if refund:
+            cls.post(new_invoices)
+            for invoice, new_invoice in itertools.izip(invoices, new_invoices):
                 if new_invoice.state == 'posted':
                     MoveLine.reconcile([l for l in invoice.lines_to_pay
                             if not l.reconciliation] +
                         [l for l in new_invoice.lines_to_pay
                             if not l.reconciliation])
-        cls.update_taxes(new_invoices)
         return new_invoices

     @classmethod
@@ -1368,10 +1362,30 @@
     @ModelView.button
     @Workflow.transition('validated')
     def validate_invoice(cls, invoices):
+        Move = Pool().get('account.move')
+
+        to_create = []
         for invoice in invoices:
             if invoice.type in ('in_invoice', 'in_credit_note'):
                 invoice.set_number()
-                invoice.create_move()
+                move = invoice.get_move()
+                if move != invoice.move:
+                    to_create.append(move._save_values)
+        invoices2move = {}
+        if to_create:
+            moves = Move.create(to_create)
+            for move in moves:
+                invoices2move[move.origin.id] = move.id
+
+        to_write = []
+        for invoice in invoices:
+            values = invoice._save_values
+            if invoice.id in invoices2move:
+                values['move'] = invoices2move[invoice.id]
+            if values:
+                to_write.extend(([invoice], values))
+        if to_write:
+            cls.write(*to_write)

     @classmethod
     @ModelView.button
@@ -1379,14 +1393,29 @@
     def post(cls, invoices):
         Move = Pool().get('account.move')

-        moves = []
+        to_create = []
         for invoice in invoices:
             invoice.set_number()
-            moves.append(invoice.create_move())
-        cls.write([i for i in invoices if i.state != 'posted'], {
-                'state': 'posted',
-                })
-        Move.post([m for m in moves if m.state != 'posted'])
+            move = invoice.get_move()
+            if move != invoice.move:
+                to_create.append(move._save_values)
+        invoices2move = {}
+        if to_create:
+            moves = Move.create(to_create)
+            for move in moves:
+                invoices2move[move.origin.id] = move.id
+        to_write = []
+        for invoice in invoices:
+            values = invoice._save_values
+            if invoice.id in invoices2move:
+                values['move'] = invoices2move[invoice.id]
+            if values:
+                to_write.extend(([invoice], values))
+        if to_write:
+            with Transaction().set_context(skip_update_taxes=True):
+                cls.write(*to_write)
+        cls.write(invoices, {'state': 'posted'})
+        Move.post([i.move for i in invoices if i.move.state != 'posted'])
         for invoice in invoices:
             if invoice.type in ('out_invoice', 'out_credit_note'):
                 invoice.print_invoice()
@@ -1425,14 +1454,17 @@

         cancel_moves = []
         delete_moves = []
+        to_write = []
         for invoice in invoices:
             if invoice.move:
                 if invoice.move.state == 'draft':
                     delete_moves.append(invoice.move)
                 elif not invoice.cancel_move:
                     invoice.cancel_move = invoice.move.cancel()
-                    invoice.save()
                     cancel_moves.append(invoice.cancel_move)
+            to_write.extend(([invoice], invoice._save_values))
+        if to_write:
+            cls.write(*to_write)
         if delete_moves:
             Move.delete(delete_moves)
         if cancel_moves:
@@ -1751,8 +1783,7 @@
         context = self.invoice.get_tax_context()
         taxes_keys = []
         with Transaction().set_context(**context):
-            taxes = Tax.compute(Tax.browse(self.taxes),
-                self.unit_price, self.quantity)
+            taxes = Tax.compute(self.taxes, self.unit_price, self.quantity)
         for tax in taxes:
             key, _ = Invoice._compute_tax(tax, self.invoice.type)
             taxes_keys.append(key)
@@ -2000,14 +2031,14 @@
         pool = Pool()
         Tax = pool.get('account.tax')
         Currency = pool.get('currency.currency')
+        TaxLine = pool.get('account.tax.line')

         context = self.invoice.get_tax_context()
         res = []
         if self.type != 'line':
             return res
         with Transaction().set_context(**context):
-            taxes = Tax.compute(Tax.browse(self.taxes),
-                self.unit_price, self.quantity)
+            taxes = Tax.compute(self.taxes, self.unit_price, self.quantity)
         for tax in taxes:
             if self.invoice.type in ('out_invoice', 'in_invoice'):
                 base_code_id = (tax['tax'].invoice_base_code.id
@@ -2022,59 +2053,61 @@
                         date=self.invoice.currency_date):
                     amount = Currency.compute(self.invoice.currency,
                         amount, self.invoice.company.currency)
-                res.append({
-                        'code': base_code_id,
-                        'amount': amount,
-                        'tax': tax['tax'].id if tax['tax'] else None,
-                        })
+                tax_line = TaxLine()
+                tax_line.code = base_code_id
+                tax_line.amount = amount
+                tax_line.tax = tax['tax']
+                res.append(tax_line)
         return res

     def get_move_line(self):
         '''
-        Return a list of move lines values for invoice line
+        Return a list of move lines instances for invoice line
         '''
-        Currency = Pool().get('currency.currency')
-        res = {}
+        pool = Pool()
+        Currency = pool.get('currency.currency')
+        MoveLine = pool.get('account.move.line')
         if self.type != 'line':
             return []
-        res['description'] = self.description
+        line = MoveLine()
+        line.description = self.description
         if self.invoice.currency != self.invoice.company.currency:
             with Transaction().set_context(date=self.invoice.currency_date):
                 amount = Currency.compute(self.invoice.currency,
                     self.amount, self.invoice.company.currency)
-            res['amount_second_currency'] = self.amount
-            res['second_currency'] = self.invoice.currency.id
+            line.amount_second_currency = self.amount
+            line.second_currency = self.invoice.currency.id
         else:
             amount = self.amount
-            res['amount_second_currency'] = None
-            res['second_currency'] = None
+            line.amount_second_currency = None
+            line.second_currency = None
         if self.invoice.type in ('in_invoice', 'out_credit_note'):
             if amount >= Decimal('0.0'):
-                res['debit'] = amount
-                res['credit'] = Decimal('0.0')
+                line.debit = amount
+                line.credit = Decimal('0.0')
             else:
-                res['debit'] = Decimal('0.0')
-                res['credit'] = - amount
-                if res['amount_second_currency']:
-                    res['amount_second_currency'] = \
-                        - res['amount_second_currency']
+                line.debit = Decimal('0.0')
+                line.credit = -amount
+                if line.amount_second_currency:
+                    line.amount_second_currency = \
+                        - line.amount_second_currency
         else:
             if amount >= Decimal('0.0'):
-                res['debit'] = Decimal('0.0')
-                res['credit'] = amount
-                if res['amount_second_currency']:
-                    res['amount_second_currency'] = \
-                        - res['amount_second_currency']
+                line.debit = Decimal('0.0')
+                line.credit = amount
+                if line.amount_second_currency:
+                    line.amount_second_currency = \
+                        - line.amount_second_currency
             else:
-                res['debit'] = - amount
-                res['credit'] = Decimal('0.0')
-        res['account'] = self.account.id
+                line.debit = -amount
+                line.credit = Decimal('0.0')
+        line.account = self.account.id
         if self.account.party_required:
-            res['party'] = self.invoice.party.id
+            line.party = self.invoice.party.id
         computed_taxes = self._compute_taxes()
         if computed_taxes:
-            res['tax_lines'] = [('create', [tax for tax in computed_taxes])]
-        return [res]
+            line.tax_lines = computed_taxes
+        return [line]

     def _credit(self):
         '''
@@ -2294,53 +2327,56 @@

     def get_move_line(self):
         '''
-        Return a list of move lines values for invoice tax
+        Return a list of move lines instances for invoice tax
         '''
-        Currency = Pool().get('currency.currency')
-        res = {}
+        pool = Pool()
+        Currency = pool.get('currency.currency')
+        MoveLine = pool.get('account.move.line')
+        TaxLine = pool.get('account.tax.line')
+        line = MoveLine()
         if not self.amount:
             return []
-        res['description'] = self.description
+        line.description = self.description
         if self.invoice.currency != self.invoice.company.currency:
             with Transaction().set_context(date=self.invoice.currency_date):
                 amount = Currency.compute(self.invoice.currency, self.amount,
                     self.invoice.company.currency)
-            res['amount_second_currency'] = self.amount
-            res['second_currency'] = self.invoice.currency.id
+            line.amount_second_currency = self.amount
+            line.second_currency = self.invoice.currency.id
         else:
             amount = self.amount
-            res['amount_second_currency'] = None
-            res['second_currency'] = None
+            line.amount_second_currency = None
+            line.second_currency = None
         if self.invoice.type in ('in_invoice', 'out_credit_note'):
             if amount >= Decimal('0.0'):
-                res['debit'] = amount
-                res['credit'] = Decimal('0.0')
+                line.debit = amount
+                line.credit = Decimal('0.0')
             else:
-                res['debit'] = Decimal('0.0')
-                res['credit'] = - amount
-                if res['amount_second_currency']:
-                    res['amount_second_currency'] = \
-                        - res['amount_second_currency']
+                line.debit = Decimal('0.0')
+                line.credit = -amount
+                if line.amount_second_currency:
+                    line.amount_second_currency = \
+                        - line.amount_second_currency
         else:
             if amount >= Decimal('0.0'):
-                res['debit'] = Decimal('0.0')
-                res['credit'] = amount
-                if res['amount_second_currency']:
-                    res['amount_second_currency'] = \
-                        - res['amount_second_currency']
+                line.debit = Decimal('0.0')
+                line.credit = amount
+                if line.amount_second_currency:
+                    line.amount_second_currency = \
+                        - line.amount_second_currency
             else:
-                res['debit'] = - amount
-                res['credit'] = Decimal('0.0')
-        res['account'] = self.account.id
+                line.debit = -amount
+                line.credit = Decimal('0.0')
+        line.account = self.account.id
         if self.account.party_required:
-            res['party'] = self.invoice.party.id
+            line.party = self.invoice.party.id
         if self.tax_code:
-            res['tax_lines'] = [('create', [{
-                            'code': self.tax_code.id,
-                            'amount': amount * self.tax_sign,
-                            'tax': self.tax and self.tax.id or None
-                            }])]
-        return [res]
+            tax_line = TaxLine()
+            tax_line.code = self.tax_code
+            tax_line.amount = amount * self.tax_sign
+            tax_line.tax = self.tax
+            line.tax_lines = [tax_line]
+        return [line]

     def _credit(self):
         '''
diff -r 0e69764f2826 trytond/trytond/modules/account_payment_type/invoice.py
--- a/trytond/trytond/modules/account_payment_type/invoice.py	Tue Jul 07 10:10:50 2015 +0200
+++ b/trytond/trytond/modules/account_payment_type/invoice.py	Tue Jul 07 17:06:02 2015 +0200
@@ -59,10 +59,10 @@
         return res

     def _get_move_line(self, date, amount):
-        res = super(Invoice, self)._get_move_line(date, amount)
+        line = super(Invoice, self)._get_move_line(date, amount)
         if self.payment_type:
-            res['payment_type'] = self.payment_type
-        return res
+            line.payment_type = self.payment_type
+        return line

     @classmethod
     def compute_default_payment_type(cls, values):
diff -r 6429c9c53cb8 trytond/trytond/modules/account_bank/account.py
--- a/trytond/trytond/modules/account_bank/account.py	Tue May 05 14:36:02 2015 +0200
+++ b/trytond/trytond/modules/account_bank/account.py	Tue Jul 07 15:36:26 2015 +0200
@@ -179,10 +179,10 @@
         '''
         Add account bank to move line when post invoice.
         '''
-        res = super(Invoice, self)._get_move_line(date, amount)
+        line = super(Invoice, self)._get_move_line(date, amount)
         if self.bank_account:
-            res['bank_account'] = self.bank_account
-        return res
+            line.bank_account = self.bank_account
+        return line

     @classmethod
     def create(cls, vlist):
diff -r 95d77335bdd5 trytond/trytond/modules/analytic_invoice/invoice.py
--- a/trytond/trytond/modules/analytic_invoice/invoice.py	Sun Mar 01 15:34:41 2015 +0100
+++ b/trytond/trytond/modules/analytic_invoice/invoice.py	Mon Nov 30 14:24:25 2015 +0100
@@ -192,26 +192,26 @@
         return result

     def get_move_line(self):
-        values = super(InvoiceLine, self).get_move_line()
+        pool = Pool()
+        AnalyticLine = pool.get('analytic_account.line')
+        Date = pool.get('ir.date')
+        lines = super(InvoiceLine, self).get_move_line()
         if self.analytic_accounts and self.analytic_accounts.accounts:
-            for value in values:
-                value['analytic_lines'] = []
-                to_create = []
+            for line in lines:
+                line.analytic_lines = []
                 for account in self.analytic_accounts.accounts:
-                    vals = {}
-                    vals['name'] = self.description
-                    vals['debit'] = value['debit']
-                    vals['credit'] = value['credit']
-                    vals['account'] = account.id
-                    vals['journal'] = self.invoice.journal.id
-                    vals['date'] = (self.invoice.accounting_date
-                        or self.invoice.invoice_date)
-                    vals['reference'] = self.invoice.reference
-                    vals['party'] = self.invoice.party.id
-                    to_create.append(vals)
-                if to_create:
-                    value['analytic_lines'] = [('create', to_create)]
-        return values
+                    analytic_line = AnalyticLine()
+                    analytic_line.name = self.description
+                    analytic_line.debit = line.debit
+                    analytic_line.credit = line.credit
+                    analytic_line.account = account
+                    analytic_line.journal = self.invoice.journal
+                    analytic_line.date = (self.invoice.accounting_date
+                        or self.invoice.invoice_date or Date.today())
+                    analytic_line.reference = self.invoice.reference
+                    analytic_line.party = self.invoice.party
+                    line.analytic_lines.append(analytic_line)
+        return lines


 class Account(ModelSQL, ModelView):