diff --git a/doc/whats-new.rst b/doc/whats-new.rst
index 93f335e625b..effb199f18e 100644
--- a/doc/whats-new.rst
+++ b/doc/whats-new.rst
@@ -26,6 +26,10 @@ Deprecations
 Bug Fixes
 ~~~~~~~~~
 
+- Fix a major performance regression in :py:meth:`Coordinates.to_index` (and
+  consequently :py:meth:`Dataset.to_dataframe`) caused by converting the cached
+  code ndarrays into Python lists (:issue:`11305`).
+
 
 Documentation
 ~~~~~~~~~~~~~
diff --git a/xarray/core/coordinates.py b/xarray/core/coordinates.py
index 85a9d97abeb..a8d5b724746 100644
--- a/xarray/core/coordinates.py
+++ b/xarray/core/coordinates.py
@@ -194,7 +194,7 @@ def to_index(self, ordered_dims: Sequence[Hashable] | None = None) -> pd.Index:
 
         return pd.MultiIndex(
             levels=level_list,  # type: ignore[arg-type,unused-ignore]
-            codes=[list(c) for c in code_list],
+            codes=code_list,  # type: ignore[arg-type,unused-ignore]
             names=names,
         )