diff --git a/frappe/__init__.py b/frappe/__init__.py
index 37c282f04a..10c8afbf23 100644
--- a/frappe/__init__.py
+++ b/frappe/__init__.py
@@ -55,29 +55,23 @@ controllers = {}
 class _dict(dict):
 	"""dict like object that exposes keys as attributes"""
 
-	def __getattr__(self, key):
-		ret = self.get(key)
-		# "__deepcopy__" exception added to fix frappe#14833 via DFP
-		if not ret and key.startswith("__") and key != "__deepcopy__":
-			raise AttributeError()
-		return ret
-
-	def __setattr__(self, key, value):
-		self[key] = value
+	__slots__ = ()
+	__getattr__ = dict.get
+	__setattr__ = dict.__setitem__
+	__delattr__ = dict.__delitem__
+	__setstate__ = dict.update
 
 	def __getstate__(self):
 		return self
 
-	def __setstate__(self, d):
-		self.update(d)
-
-	def update(self, d):
+	def update(self, *args, **kwargs):
 		"""update and return self -- the missing dict feature in python"""
-		super(_dict, self).update(d)
+
+		super().update(*args, **kwargs)
 		return self
 
 	def copy(self):
-		return _dict(dict(self).copy())
+		return _dict(self)
 
 
 def _(msg, lang=None, context=None):
diff --git a/frappe/model/meta.py b/frappe/model/meta.py
index c363e63f4f..407f7d0811 100644
--- a/frappe/model/meta.py
+++ b/frappe/model/meta.py
@@ -134,24 +134,22 @@ class Meta(Document):
 	def as_dict(self, no_nulls=False):
 		def serialize(doc):
 			out = {}
-			for key in doc.__dict__:
-				value = doc.__dict__.get(key)
-
+			for key, value in doc.__dict__.items():
 				if isinstance(value, (list, tuple)):
-					if len(value) > 0 and hasattr(value[0], "__dict__"):
-						value = [serialize(d) for d in value]
-					else:
+					if not value or not isinstance(value[0], BaseDocument):
 						# non standard list object, skip
 						continue
 
-				if isinstance(value, (str, int, float, datetime, list, tuple)) or (
-					not no_nulls and value is None
+					value = [serialize(d) for d in value]
+
+				if (not no_nulls and value is None) or isinstance(
+					value, (str, int, float, datetime, list, tuple)
 				):
 					out[key] = value
 
 			# set empty lists for unset table fields
 			for table_field in DOCTYPE_TABLE_FIELDS:
-				if not out.get(table_field.fieldname):
+				if out.get(table_field.fieldname) is None:
 					out[table_field.fieldname] = []
 
 			return out