diff --git a/.gitignore b/.gitignore
index 399a111..73c8c0f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -10,6 +10,7 @@
 .idea/**/usage.statistics.xml
 .idea/**/dictionaries
 .idea/**/shelf
+.vscode/
 
 # Generated files
 .idea/**/contentModel.xml
diff --git a/scripts/convert.py b/scripts/convert.py
index 935a152..35169ba 100755
--- a/scripts/convert.py
+++ b/scripts/convert.py
@@ -57,7 +57,7 @@ def get_mongo_storage_by_session(client, *args, **kwargs):
         while True:
             try:
                 char = raw_input("Please enter a number or enter for all: ")
-                if char is "":
+                if char == "":
                     return client.find(*args, **kwargs)
                 return client.find_by_session_id(s_lut[int(char)]["id"], *args, **kwargs)
             except (EOFError, ValueError, IndexError):
diff --git a/src/topic_store/api.py b/src/topic_store/api.py
index 9f20bd5..68d4762 100644
--- a/src/topic_store/api.py
+++ b/src/topic_store/api.py
@@ -5,20 +5,11 @@
 
 import pathlib
 from abc import ABCMeta, abstractmethod, abstractproperty
+from .utils import abstractstatic
 
 __all__ = ["load", "Storage"]
 
 
-class abstract_static(staticmethod):
-    __slots__ = ()
-
-    def __init__(self, function):
-        super(abstract_static, self).__init__(function)
-        function.__isabstractmethod__ = True
-
-    __isabstractmethod__ = True
-
-
 class Storage:
     __metaclass__ = ABCMeta
 
@@ -26,7 +17,7 @@ class Storage:
     def suffix(self):
         raise NotImplementedError
 
-    @abstract_static
+    @abstractstatic
     def load(path):
         """Storage containers must have a load mechanism"""''
         raise NotImplementedError
diff --git a/src/topic_store/data.py b/src/topic_store/data.py
index 9cc7497..7c489ef 100644
--- a/src/topic_store/data.py
+++ b/src/topic_store/data.py
@@ -12,6 +12,7 @@
 import roslib.message
 import rospy
 from genpy import Message as ROSMessage
+from .utils import cached_property
 
 try:
     from collections import Mapping as MappingType
@@ -211,18 +212,29 @@ def __init__(self, data_tree):
         if not isinstance(data_tree, dict):
             raise ValueError("Data tree must be a dict to construct a TopicStore")
         # Ensure passed data tree does not contain ROS msgs
-        self.__data_tree = DefaultTypeParser()(data_tree)
-        if "_id" not in self.__data_tree:
-            self.__data_tree["_id"] = bson.ObjectId()
-        if "_ts_meta" not in self.__data_tree:
-            self.__data_tree["_ts_meta"] = dict(session=_session_id, sys_time=time_as_ms(), ros_time=ros_time_as_ms())
+        self.data_tree = DefaultTypeParser()(data_tree)
+        if "_id" not in self.data_tree:
+            self.data_tree["_id"] = bson.ObjectId()
+        if "_ts_meta" not in self.data_tree:
+            self.data_tree["_ts_meta"] = dict(session=_session_id, sys_time=time_as_ms(), ros_time=ros_time_as_ms())
         # Cache for dict to ROS message parsing
         self.__msgs = None
 
     @property
-    def dict(self):
+    def data_tree(self):
         return self.__data_tree
 
+    @data_tree.setter
+    def data_tree(self, value):
+        # clears variable cache
+        del self.to_ros_msg_list
+        del self.flatten_ros_msg_dict
+        self.__data_tree = value
+
+    @property
+    def dict(self):
+        return self.data_tree
+
     @property
     def msgs(self):
         if self.__msgs is None:
@@ -418,10 +430,10 @@ def __ros_msg_dict_to_list(ros_msg_dict, return_keys=False, parent=""):
             for ret in TopicStore.__ros_msg_dict_to_list(value, return_keys, key if not parent else parent + "." + key):
                 yield ret
 
+    @cached_property
     def to_ros_msg_list(self):
-        # TODO: Cache this operation until self.__data_tree updated
         return list(TopicStore.__ros_msg_dict_to_list(self.msgs))
 
+    @cached_property
     def flatten_ros_msg_dict(self):
-        # TODO: Cache this operation until self.__data_tree updated
         return {k: v for k, v in TopicStore.__ros_msg_dict_to_list(self.msgs, return_keys=True)}
diff --git a/src/topic_store/utils.py b/src/topic_store/utils.py
new file mode 100644
index 0000000..51c8e41
--- /dev/null
+++ b/src/topic_store/utils.py
@@ -0,0 +1,32 @@
+#  Peter Lightbody (pet1330) Copyright (c) 2020
+#  Email: pet1330@gmail.com
+
+
+"""A decorator to cache instance variables"""
+class cached_property(property):
+    def __init__(self, method):
+        self.method = method
+
+    def __set__(self, obj, value):
+        obj.__dict__[self.method.__name__] = value
+
+    def __delete__(self, obj):
+        del obj.__dict__[self.method.__name__]
+
+    def __get__(self, obj, type=None):
+        if obj is None:
+            return self
+
+        if not self.method.__name__ in obj.__dict__:
+            obj.__dict__[self.method.__name__] = self.method(obj)
+        return obj.__dict__[self.method.__name__]
+
+
+class abstractstatic(staticmethod):
+    __slots__ = ()
+
+    def __init__(self, function):
+        super(abstractstatic, self).__init__(function)
+        function.__isabstractmethod__ = True
+
+    __isabstractmethod__ = True