diff --git a/radicale/__init__.py b/radicale/__init__.py
index 8b8085c..9fc9fc4 100644
--- a/radicale/__init__.py
+++ b/radicale/__init__.py
@@ -3,7 +3,7 @@
 # This file is part of Radicale Server - Calendar Server
 # Copyright © 2008 Nicolas Kandel
 # Copyright © 2008 Pascal Halter
-# Copyright © 2008-2013 Guillaume Ayoub
+# Copyright © 2008-2015 Guillaume Ayoub
 #
 # This library is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -377,8 +377,8 @@ class Application(object):
             item = collection
         else:
             # Try to get an item matching the path
-            item = collection.get_item(
-                xmlutils.name_from_path(environ["PATH_INFO"], collection))
+            name = xmlutils.name_from_path(environ["PATH_INFO"], collection)
+            item = collection.items.get(name)
 
         if item:
             # Evolution bug workaround
@@ -414,7 +414,7 @@ class Application(object):
 
         if item_name:
             # Get collection item
-            item = collection.get_item(item_name)
+            item = collection.items[item_name]
             if item:
                 items = [item]
                 if collection.resource_type == "calendar":
@@ -500,7 +500,7 @@ class Application(object):
         from_name = xmlutils.name_from_path(
             environ["PATH_INFO"], from_collection)
         if from_name:
-            item = from_collection.get_item(from_name)
+            item = from_collection.items.get(from_name)
             if item:
                 # Move the item
                 to_url_parts = urlparse(environ["HTTP_DESTINATION"])
@@ -571,7 +571,7 @@ class Application(object):
         collection.set_mimetype(environ.get("CONTENT_TYPE"))
         headers = {}
         item_name = xmlutils.name_from_path(environ["PATH_INFO"], collection)
-        item = collection.get_item(item_name)
+        item = collection.items.get(item_name)
 
         # Evolution bug workaround
         etag = environ.get("HTTP_IF_MATCH", "").replace("\\", "")
@@ -588,7 +588,7 @@ class Application(object):
             # If the added item doesn't have the same name as the one given
             # by the client, then there's no obvious way to generate an
             # etag, we can safely ignore it.
-            new_item = collection.get_item(item_name)
+            new_item = collection.items.get(item_name)
             if new_item:
                 headers["ETag"] = new_item.etag
         else:
diff --git a/radicale/ical.py b/radicale/ical.py
index 1d3494a..b9f31fc 100644
--- a/radicale/ical.py
+++ b/radicale/ical.py
@@ -3,7 +3,7 @@
 # This file is part of Radicale Server - Calendar Server
 # Copyright © 2008 Nicolas Kandel
 # Copyright © 2008 Pascal Halter
-# Copyright © 2008-2013 Guillaume Ayoub
+# Copyright © 2008-2015 Guillaume Ayoub
 #
 # This library is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -194,8 +194,7 @@ class Collection(object):
         else:
             self.owner = None
         self.is_principal = principal
-        self._items = self._parse(
-            self.text, (Event, Todo, Journal, Card, Timezone))
+        self._items = None
 
     @classmethod
     def from_path(cls, path, depth="1", include_container=True):
@@ -346,10 +345,6 @@ class Collection(object):
 
         return items
 
-    def get_item(self, name):
-        """Get item named ``name`` from collection."""
-        return self._items.get(name)
-
     def append(self, name, text):
         """Append items from ``text`` to collection.
 
@@ -359,14 +354,14 @@ class Collection(object):
         new_items = self._parse(
             text, (Timezone, Event, Todo, Journal, Card), name)
         for new_item in new_items.values():
-            if new_item.name not in self._items:
-                self._items[new_item] = new_item
+            if new_item.name not in self.items:
+                self.items[new_item] = new_item
         self.write()
 
     def remove(self, name):
         """Remove object named ``name`` from collection."""
-        if name in self._items:
-            del self._items[name]
+        if name in self.items:
+            del self.items[name]
         self.write()
 
     def replace(self, name, text):
@@ -376,7 +371,7 @@ class Collection(object):
 
     def write(self):
         """Write collection with given parameters."""
-        text = serialize(self.tag, self.headers, self.items)
+        text = serialize(self.tag, self.headers, self.items.values())
         self.save(text)
 
     def set_mimetype(self, mimetype):
@@ -459,44 +454,25 @@ class Collection(object):
             Header("PRODID:-//Radicale//NONSGML Radicale Server//EN"),
             Header("VERSION:%s" % self.version))
 
-    def filter_items(self, *item_types):
-        tags = [item_type.tag for item_type in item_types]
-        return [item for item in self.items if item.tag in tags]
-
     @property
     def items(self):
         """Get list of all items in collection."""
-        return list(self._items.values())
+        if self._items is None:
+            self._items = self._parse(
+                self.text, (Event, Todo, Journal, Card, Timezone))
+        return self._items
+
+    @property
+    def timezones(self):
+        """Get list of all timezones in collection."""
+        return [
+            item for item in self.items.values() if item.tag == Timezone.tag]
 
     @property
     def components(self):
         """Get list of all components in collection."""
-        return self.filter_items(Event, Todo, Journal, Card)
-
-    @property
-    def events(self):
-        """Get list of ``Event`` items in calendar."""
-        return self.filter_items(Event)
-
-    @property
-    def todos(self):
-        """Get list of ``Todo`` items in calendar."""
-        return self.filter_items(Todo)
-
-    @property
-    def journals(self):
-        """Get list of ``Journal`` items in calendar."""
-        return self.filter_items(Journal)
-
-    @property
-    def timezones(self):
-        """Get list of ``Timezone`` items in calendar."""
-        return self.filter_items(Timezone)
-
-    @property
-    def cards(self):
-        """Get list of ``Card`` items in address book."""
-        return self.filter_items(Card)
+        tags = [item_type.tag for item_type in (Event, Todo, Journal, Card)]
+        return [item for item in self.items.values() if item.tag in tags]
 
     @property
     def owner_url(self):
diff --git a/radicale/storage/database.py b/radicale/storage/database.py
index 397d8e4..24ab42f 100644
--- a/radicale/storage/database.py
+++ b/radicale/storage/database.py
@@ -139,12 +139,7 @@ class Collection(ical.Collection):
         """Collection's object mapped to the table line."""
         return self.session.query(DBCollection).get(self.path)
 
-    def write(self, headers=None, items=None):
-        headers = headers or self.headers or (
-            ical.Header("PRODID:-//Radicale//NONSGML Radicale Server//EN"),
-            ical.Header("VERSION:%s" % self.version))
-        items = items if items is not None else self.items
-
+    def write(self):
         if self._db_collection:
             for item in self._db_collection.items:
                 for line in item.lines:
@@ -158,13 +153,13 @@ class Collection(ical.Collection):
             db_collection.parent_path = "/".join(self.path.split("/")[:-1])
             self.session.add(db_collection)
 
-        for header in headers:
+        for header in self.headers:
             db_header = DBHeader()
             db_header.name, db_header.value = header.text.split(":", 1)
             db_header.collection_path = self.path
             self.session.add(db_header)
 
-        for item in items:
+        for item in self.items.values():
             db_item = DBItem()
             db_item.name = item.name
             db_item.tag = item.tag
@@ -258,11 +253,6 @@ class Collection(ical.Collection):
                 prop.collection_path = self.path
                 self.session.add(prop)
 
-    @property
-    def items(self):
-        return self._query(
-            (ical.Event, ical.Todo, ical.Journal, ical.Card, ical.Timezone))
-
     @property
     def components(self):
         return self._query((ical.Event, ical.Todo, ical.Journal, ical.Card))
diff --git a/radicale/storage/filesystem.py b/radicale/storage/filesystem.py
index 238f6ec..869b608 100644
--- a/radicale/storage/filesystem.py
+++ b/radicale/storage/filesystem.py
@@ -1,7 +1,7 @@
 # -*- coding: utf-8 -*-
 #
 # This file is part of Radicale Server - Calendar Server
-# Copyright © 2012-2013 Guillaume Ayoub
+# Copyright © 2012-2015 Guillaume Ayoub
 #
 # This library is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
diff --git a/radicale/storage/multifilesystem.py b/radicale/storage/multifilesystem.py
index 647d7e7..a3f7589 100644
--- a/radicale/storage/multifilesystem.py
+++ b/radicale/storage/multifilesystem.py
@@ -1,8 +1,8 @@
 # -*- coding: utf-8 -*-
 #
 # This file is part of Radicale Server - Calendar Server
-# Copyright © 2013 Guillaume Ayoub
-# Copyright © 2013 Jean-Marc Martins
+# Copyright © 2014 Jean-Marc Martins
+# Copyright © 2014-2015 Guillaume Ayoub
 #
 # This library is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -43,14 +43,11 @@ class Collection(filesystem.Collection):
             ical.Header("PRODID:-//Radicale//NONSGML Radicale Server//EN"),
             ical.Header("VERSION:%s" % self.version))
 
-    def write(self, headers=None, items=None):
+    def write(self):
         self._create_dirs()
-        headers = headers or self.headers
-        items = items if items is not None else self.items
-        timezones = list(set(i for i in items if isinstance(i, ical.Timezone)))
-        components = [i for i in items if isinstance(i, ical.Component)]
-        for component in components:
-            text = ical.serialize(self.tag, headers, [component] + timezones)
+        for component in self.components:
+            text = ical.serialize(
+                self.tag, self.headers, [component] + self.timezones)
             name = (
                 component.name if sys.version_info[0] >= 3 else
                 component.name.encode(filesystem.FILESYSTEM_ENCODING))
diff --git a/radicale/xmlutils.py b/radicale/xmlutils.py
index 17531fd..7f1573b 100644
--- a/radicale/xmlutils.py
+++ b/radicale/xmlutils.py
@@ -3,7 +3,7 @@
 # This file is part of Radicale Server - Calendar Server
 # Copyright © 2008 Nicolas Kandel
 # Copyright © 2008 Pascal Halter
-# Copyright © 2008-2013 Guillaume Ayoub
+# Copyright © 2008-2015 Guillaume Ayoub
 #
 # This library is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -445,7 +445,7 @@ def proppatch(path, xml_request, collection):
 def put(path, ical_request, collection):
     """Read PUT requests."""
     name = name_from_path(path, collection)
-    if name in (item.name for item in collection.items):
+    if name in collection.items:
         # PUT is modifying an existing item
         collection.replace(name, ical_request)
     elif name:
@@ -495,7 +495,6 @@ def report(path, xml_request, collection):
     multistatus = ET.Element(_tag("D", "multistatus"))
 
     collection_tag = collection.tag
-    collection_items = collection.items
     collection_headers = collection.headers
     collection_timezones = collection.timezones
 
@@ -505,7 +504,7 @@ def report(path, xml_request, collection):
         if name:
             # Reference is an item
             path = "/".join(hreference.split("/")[:-1]) + "/"
-            items = (item for item in collection_items if item.name == name)
+            items = [collection.items[name]]
         else:
             # Reference is a collection
             path = hreference