Speed up adding record to One2Many via on_change

There is no need to trigger a group-changed for each record added to the same
Group because it will trigger a global display and a the O2MField._group_changed
which depends only on parent.

issue3966
review6331002

tryton/gui/window/view_form/model/field.py

@@ -687,8 +687,10 @@ class O2MField(Field):
             record.value[self.name].add_fields(fields, signal=False)
             for index, vals in value.get('add', []):
                 new_record = record.value[self.name].new(default=False)
-                record.value[self.name].add(new_record, index)
+                record.value[self.name].add(new_record, index, signal=False)
                 new_record.set_on_change(vals)
+            if value.get('add'):
+                record.value[self.name].signal('group-changed', new_record)
 
             for vals in value.get('update', []):
                 if 'id' not in vals:

tryton/gui/window/view_form/model/group.py

@@ -261,7 +261,7 @@ class Group(SignalEvent, list):
 
     context = property(_get_context)
 
-    def add(self, record, position=-1):
+    def add(self, record, position=-1, signal=True):
         if record.group is not self:
             record.signal_unconnect(record.group)
             record.group = self
@@ -281,7 +281,8 @@ class Group(SignalEvent, list):
         self.current_idx = position
         record.modified_fields.setdefault('id')
         record.signal('record-modified')
-        self.signal('group-changed', record)
+        if signal:
+            self.signal('group-changed', record)
         # Set parent field to trigger on_change
         if self.parent and self.parent_name in self.fields:
             field = self.fields[self.parent_name]