diff --git a/pynamodb/attributes.py b/pynamodb/attributes.py
index 122ba0def..3f1706a25 100644
--- a/pynamodb/attributes.py
+++ b/pynamodb/attributes.py
@@ -2,7 +2,6 @@
 PynamoDB attributes
 """
 import six
-import json
 from base64 import b64encode, b64decode
 from delorean import Delorean, parse
 from pynamodb.constants import (
@@ -10,6 +9,14 @@
     DEFAULT_ENCODING
 )
 
+try:
+    import ujson as json
+    import json as python_json
+    HAS_UJSON = True
+except ImportError:
+    import json
+    HAS_UJSON = False
+
 
 class Attribute(object):
     """
@@ -183,7 +190,13 @@ def deserialize(self, value):
         """
         Deserializes JSON
         """
-        return json.loads(value, strict=False)
+        if HAS_UJSON:
+            try:
+                return json.loads(value)
+            except ValueError:
+                return python_json.loads(value, strict=False)
+        else:
+            return json.loads(value, strict=False)
 
 
 class BooleanAttribute(Attribute):
@@ -230,13 +243,26 @@ def serialize(self, value):
         """
         Encode numbers as JSON
         """
-        return json.dumps(value)
+        if HAS_UJSON and isinstance(value, float):
+            from decimal import Decimal
+            value = Decimal(value)
+        try:
+            return json.dumps(value)
+        except OverflowError:
+            if HAS_UJSON:
+                return python_json.dumps(value)
+            raise
 
     def deserialize(self, value):
         """
         Decode numbers from JSON
         """
-        return json.loads(value)
+        try:
+            return json.loads(value)
+        except ValueError:
+            if HAS_UJSON:
+                return python_json.loads(value)
+            raise
 
 
 class UTCDateTimeAttribute(Attribute):
diff --git a/pynamodb/connection/base.py b/pynamodb/connection/base.py
index a0ec1bece..dd2f47b9e 100644
--- a/pynamodb/connection/base.py
+++ b/pynamodb/connection/base.py
@@ -33,6 +33,12 @@
     ITEMS, DEFAULT_ENCODING, BINARY_SHORT, BINARY_SET_SHORT, LAST_EVALUATED_KEY, RESPONSES, UNPROCESSED_KEYS,
     UNPROCESSED_ITEMS, STREAM_SPECIFICATION, STREAM_VIEW_TYPE, STREAM_ENABLED)
 
+try:
+    import ujson as json
+except ImportError:
+    import json
+
+
 BOTOCORE_EXCEPTIONS = (BotoCoreError, ClientError)
 
 
@@ -241,8 +247,8 @@ def _make_api_call(self, operation_name, operation_kwargs):
         )
         prepared_request = self.client._endpoint.create_request(request_dict, operation_model)
         response = self.requests_session.send(prepared_request)
+        data = json.loads(response.text)
         if response.status_code >= 300:
-            data = response.json()
             botocore_expected_format = {"Error": {"Message": data.get("message", ""), "Code": data.get("__type", "")}}
             raise ClientError(botocore_expected_format, operation_name)
         data = response.json()
diff --git a/pynamodb/models.py b/pynamodb/models.py
index 80c31859f..d98085d56 100644
--- a/pynamodb/models.py
+++ b/pynamodb/models.py
@@ -1,7 +1,6 @@
 """
 DynamoDB Models for PynamoDB
 """
-import json
 import time
 import six
 import copy
@@ -32,6 +31,11 @@
     COUNT, ITEM_COUNT, KEY, UNPROCESSED_ITEMS, STREAM_VIEW_TYPE, STREAM_SPECIFICATION,
     STREAM_ENABLED)
 
+try:
+    import ujson as json
+except ImportError:
+    import json
+
 
 log = logging.getLogger(__name__)
 log.addHandler(NullHandler())
diff --git a/pynamodb/tests/test_attributes.py b/pynamodb/tests/test_attributes.py
index 202101710..72b47f8b9 100644
--- a/pynamodb/tests/test_attributes.py
+++ b/pynamodb/tests/test_attributes.py
@@ -2,7 +2,6 @@
 pynamodb attributes tests
 """
 import six
-import json
 from base64 import b64encode
 from datetime import datetime
 from delorean import Delorean
@@ -15,6 +14,11 @@
     JSONAttribute, DEFAULT_ENCODING, NUMBER, STRING, STRING_SET, NUMBER_SET, BINARY_SET,
     BINARY)
 
+try:
+    import ujson as json
+except ImportError:
+    import json
+
 
 class AttributeTestModel(Model):