Used the cached_property decorator on the serializer object and the field object.

rest_framework/fields.py

@@ -6,6 +6,7 @@ from django.utils import six, timezone
 from django.utils.datastructures import SortedDict
 from django.utils.dateparse import parse_date, parse_datetime, parse_time
 from django.utils.encoding import is_protected_type
+from django.utils.functional import cached_property
 from django.utils.translation import ugettext_lazy as _
 from rest_framework import ISO_8601
 from rest_framework.compat import smart_text, EmailValidator, MinValueValidator, MaxValueValidator, URLValidator
@@ -296,7 +297,7 @@ class Field(object):
             raise AssertionError(msg)
         raise ValidationError(msg.format(**kwargs))
 
-    @property
+    @cached_property
     def root(self):
         """
         Returns the top-level serializer for this field.
@@ -306,7 +307,7 @@ class Field(object):
             root = root.parent
         return root
 
-    @property
+    @cached_property
     def context(self):
         """
         Returns the context as passed to the root serializer on initialization.

rest_framework/serializers.py

@@ -15,6 +15,7 @@ from django.db import models
 from django.utils import six
 from django.utils.datastructures import SortedDict
 from collections import namedtuple
+from django.utils.functional import cached_property
 from rest_framework.fields import empty, set_value, Field, SkipField
 from rest_framework.settings import api_settings
 from rest_framework.utils import html, model_meta, representation
@@ -108,28 +109,26 @@ class BaseSerializer(Field):
 
         return not bool(self._errors)
 
-    @property
+    @cached_property
     def data(self):
-        if not hasattr(self, '_data'):
-            if self.instance is not None:
-                self._data = self.to_representation(self.instance)
-            elif self._initial_data is not None:
-                self._data = dict([
-                    (field_name, field.get_value(self._initial_data))
-                    for field_name, field in self.fields.items()
-                ])
-            else:
-                self._data = self.get_initial()
-        return self._data
+        if self.instance is not None:
+            return self.to_representation(self.instance)
+        elif self._initial_data is not None:
+            return dict([
+                (field_name, field.get_value(self._initial_data))
+                for field_name, field in self.fields.items()
+            ])
+        else:
+            return self.get_initial()
 
-    @property
+    @cached_property
     def errors(self):
         if not hasattr(self, '_errors'):
             msg = 'You must call `.is_valid()` before accessing `.errors`.'
             raise AssertionError(msg)
         return self._errors
 
-    @property
+    @cached_property
     def validated_data(self):
         if not hasattr(self, '_validated_data'):
             msg = 'You must call `.is_valid()` before accessing `.validated_data`.'