diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2026-07-06-14-25-00.gh-issue-153199.abc123.rst b/Misc/NEWS.d/next/Core_and_Builtins/2026-07-06-14-25-00.gh-issue-153199.abc123.rst
new file mode 100644
index 000000000000000..cde48ce212720a3
--- /dev/null
+++ b/Misc/NEWS.d/next/Core_and_Builtins/2026-07-06-14-25-00.gh-issue-153199.abc123.rst
@@ -0,0 +1 @@
+Optimize set and frozenset membership lookup by inlining ``set_do_lookup`` and adding a ``PyUnicode_CheckExact`` fast path to ``set_compare_frozenset``.
diff --git a/Objects/setobject.c b/Objects/setobject.c
index 8fdd1eb26118c0a..a981849cc859d4a 100644
--- a/Objects/setobject.c
+++ b/Objects/setobject.c
@@ -166,8 +166,7 @@ set_compare_entry_lock_held(PySetObject *so, setentry *table, setentry *entry,
 
 // This is similar to set_compare_entry_lock_held() but we don't need to
 // incref startkey before comparing and we don't need to check if the set has
-// changed.  This also omits the PyUnicode_CheckExact() special case since it
-// doesn't help much for frozensets.
+// changed.
 static inline Py_ALWAYS_INLINE int
 set_compare_frozenset(PySetObject *so, setentry *table, setentry *ep,
                                  PyObject *key, Py_hash_t hash)
@@ -182,6 +181,11 @@ set_compare_frozenset(PySetObject *so, setentry *table, setentry *ep,
     }
     Py_ssize_t ep_hash = ep->hash;
     if (ep_hash == hash) {
+        if (PyUnicode_CheckExact(startkey)
+            && PyUnicode_CheckExact(key)
+            && unicode_eq(startkey, key)) {
+            return SET_LOOKKEY_FOUND;
+        }
         int cmp = PyObject_RichCompareBool(startkey, key, Py_EQ);
         if (cmp < 0) {
             return SET_LOOKKEY_ERROR;
@@ -217,7 +221,7 @@ set_zero_table(setentry *table, size_t size)
 /* This must be >= 1 */
 #define PERTURB_SHIFT 5
 
-static int
+static inline Py_ALWAYS_INLINE int
 set_do_lookup(PySetObject *so, setentry *table, size_t mask, PyObject *key,
               Py_hash_t hash, setentry **epp, compare_func compare_entry)
 {