diff --git a/drafthorse/models/container.py b/drafthorse/models/container.py
index f5ec87e..30cdfe3 100644
--- a/drafthorse/models/container.py
+++ b/drafthorse/models/container.py
@@ -1,4 +1,6 @@
 class Container:
+    __slots__ = ("children", "child_type")
+
     def __init__(self, child_type):
         super().__init__()
         self.children = []
@@ -26,6 +28,8 @@ def add_from_etree(self, root, strict=True):
 
 
 class SimpleContainer(Container):
+    __slots__ = ("children", "child_type", "namespace", "tag")
+
     def __init__(self, child_type, namespace, tag):
         super().__init__(child_type)
         self.namespace = namespace
@@ -51,6 +55,8 @@ def add_from_etree(self, root, strict=True):
 
 
 class CurrencyContainer(SimpleContainer):
+    __slots__ = ("children", "child_type", "namespace", "tag")
+
     def empty_element(self):
         from .elements import CurrencyElement
 
@@ -65,6 +71,8 @@ def add_from_etree(self, root, strict=True):
 
 
 class IDContainer(SimpleContainer):
+    __slots__ = ("children", "child_type", "namespace", "tag")
+
     def empty_element(self):
         from .elements import IDElement
 
@@ -79,6 +87,8 @@ def add_from_etree(self, root, strict=True):
 
 
 class StringContainer(SimpleContainer):
+    __slots__ = ("children", "child_type", "namespace", "tag")
+
     def empty_element(self):
         from .elements import StringElement