diff --git a/django/forms/models.py b/django/forms/models.py
index b23d815775..acb7f91a76 100644
--- a/django/forms/models.py
+++ b/django/forms/models.py
@@ -1083,12 +1083,12 @@ class ModelChoiceIterator(object):
         if self.field.cache_choices:
             if self.field.choice_cache is None:
                 self.field.choice_cache = [
-                    self.choice(obj) for obj in self.queryset.all()
+                    self.choice(obj) for obj in self.queryset.iterator()
                 ]
             for choice in self.field.choice_cache:
                 yield choice
         else:
-            for obj in self.queryset.all():
+            for obj in self.queryset.iterator():
                 yield self.choice(obj)
 
     def __len__(self):