diff --git a/Lib/_collections_abc.py b/Lib/_collections_abc.py
index 51263d696a1777..ad2f01b9653603 100644
--- a/Lib/_collections_abc.py
+++ b/Lib/_collections_abc.py
@@ -967,8 +967,8 @@ def update(self, other=(), /, **kwds):
             In either case, this is followed by: for k, v in F.items(): D[k] = v
         '''
         if isinstance(other, Mapping):
-            for key in other:
-                self[key] = other[key]
+            for key, value in other.items():
+                self[key] = value
         elif hasattr(other, "keys"):
             for key in other.keys():
                 self[key] = other[key]
diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2025-06-16-18-16-41.gh-issue-135575._N5rTH.rst b/Misc/NEWS.d/next/Core_and_Builtins/2025-06-16-18-16-41.gh-issue-135575._N5rTH.rst
new file mode 100644
index 00000000000000..5b5bef87bd4949
--- /dev/null
+++ b/Misc/NEWS.d/next/Core_and_Builtins/2025-06-16-18-16-41.gh-issue-135575._N5rTH.rst
@@ -0,0 +1 @@
+Improved performance of :meth:`collections.abc.MutableMapping.update`.