diff --git a/django/db/models/base.py b/django/db/models/base.py
index 1f7e5f84aa..cb51ed42c4 100644
--- a/django/db/models/base.py
+++ b/django/db/models/base.py
@@ -799,15 +799,7 @@ class Model(metaclass=ModelBase):
                 return
 
             update_fields = frozenset(update_fields)
-            field_names = set()
-
-            for field in self._meta.concrete_fields:
-                if not field.primary_key:
-                    field_names.add(field.name)
-
-                    if field.name != field.attname:
-                        field_names.add(field.attname)
-
+            field_names = self._meta._non_pk_concrete_field_names
             non_model_fields = update_fields.difference(field_names)
 
             if non_model_fields:
diff --git a/django/db/models/options.py b/django/db/models/options.py
index bff55011dc..b6b8202802 100644
--- a/django/db/models/options.py
+++ b/django/db/models/options.py
@@ -89,6 +89,7 @@ class Options:
         "many_to_many",
         "concrete_fields",
         "local_concrete_fields",
+        "_non_pk_concrete_field_names",
         "_forward_fields_map",
         "managers",
         "managers_map",
@@ -982,6 +983,19 @@ class Options:
                 names.append(name)
         return frozenset(names)
 
+    @cached_property
+    def _non_pk_concrete_field_names(self):
+        """
+        Return a set of the non-pk concrete field names defined on the model.
+        """
+        names = []
+        for field in self.concrete_fields:
+            if not field.primary_key:
+                names.append(field.name)
+                if field.name != field.attname:
+                    names.append(field.attname)
+        return frozenset(names)
+
     @cached_property
     def db_returning_fields(self):
         """