diff --git a/Lib/test/test_clinic.py b/Lib/test/test_clinic.py
index f5334f70768dc4..ebf2e446ef056b 100644
--- a/Lib/test/test_clinic.py
+++ b/Lib/test/test_clinic.py
@@ -3262,8 +3262,6 @@ def test_vectorcall_on_init(self):
             class Foo "FooObject *" "Foo_Type"
             @vectorcall
             Foo.__init__
-                iterable: object = NULL
-                /
         """
         func = self.parse_function(block, signatures_in_block=3,
                                    function_index=2)
@@ -3294,14 +3292,16 @@ class Foo "FooObject *" "Foo_Type"
         self.expect_failure(block, err, lineno=2)
 
     def test_vectorcall_without_type_object(self):
-        err = "@vectorcall requires the type object of 'Foo'"
+        # Heap types have no C pointer to name, so the type object is optional.
         block = """
             module m
             class Foo "FooObject *" ""
             @vectorcall
             Foo.__init__
         """
-        self.expect_failure(block, err, lineno=3)
+        func = self.parse_function(block, signatures_in_block=3,
+                                   function_index=2)
+        self.assertTrue(func.vectorcall)
 
     def test_vectorcall_unsupported_converter(self):
         # str(encoding=...) has no parse_arg() implementation.
diff --git a/Misc/NEWS.d/next/Library/2026-09-26-05-18-21.gh-issue-144650.zqHLOW.rst b/Misc/NEWS.d/next/Library/2026-09-26-05-18-21.gh-issue-144650.zqHLOW.rst
new file mode 100644
index 00000000000000..34a0c0246d3ee8
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-09-26-05-18-21.gh-issue-144650.zqHLOW.rst
@@ -0,0 +1,2 @@
+Use AC vectorcall support for the :class:`decimal.Decimal`.  This offers
+~1.15x speedup on creation of small instances.
diff --git a/Modules/_decimal/_decimal.c b/Modules/_decimal/_decimal.c
index ada9b02d690717..cbcb3bf55463f0 100644
--- a/Modules/_decimal/_decimal.c
+++ b/Modules/_decimal/_decimal.c
@@ -57,6 +57,8 @@
   #define _PY_DEC_ROUND_GUARD (MPD_ROUND_GUARD-1)
 #endif
 
+static PyType_Spec dec_spec;
+
 #include "clinic/_decimal.c.h"
 
 #define MPD_SPEC_VERSION "1.70"  // Highest version of the spec this complies with
@@ -132,7 +134,6 @@ get_module_state(PyObject *mod)
 }
 
 static struct PyModuleDef _decimal_module;
-static PyType_Spec dec_spec;
 static PyType_Spec context_spec;
 
 static inline decimal_state *
@@ -3309,6 +3310,7 @@ PyDec_FromObject(PyObject *v, PyObject *context)
 }
 
 /*[clinic input]
+@vectorcall
 @classmethod
 _decimal.Decimal.__new__ as dec_new
 
@@ -3325,7 +3327,7 @@ trap is active.
 
 static PyObject *
 dec_new_impl(PyTypeObject *type, PyObject *value, PyObject *context)
-/*[clinic end generated code: output=35f48a40c65625ba input=5f8a0892d3fcef80]*/
+/*[clinic end generated code: output=35f48a40c65625ba input=0e5ca99183562cd9]*/
 {
     decimal_state *state = get_module_state_by_def(type);
     CONTEXT_CHECK_VA(state, context);
@@ -6186,6 +6188,7 @@ static PyType_Slot dec_slots[] = {
     {Py_tp_methods, dec_methods},
     {Py_tp_getset, dec_getsets},
     {Py_tp_new, dec_new},
+    {Py_tp_vectorcall, dec_vectorcall},
 
     // Number protocol
     {Py_nb_add, nm_mpd_qadd},
diff --git a/Modules/_decimal/clinic/_decimal.c.h b/Modules/_decimal/clinic/_decimal.c.h
index 8ad883d8a2d14d..c188e9e61664b8 100644
--- a/Modules/_decimal/clinic/_decimal.c.h
+++ b/Modules/_decimal/clinic/_decimal.c.h
@@ -878,7 +878,8 @@ static PyObject *
 dec_new_impl(PyTypeObject *type, PyObject *value, PyObject *context);
 
 static PyObject *
-dec_new(PyTypeObject *type, PyObject *args, PyObject *kwargs)
+dec_new_helper(PyTypeObject *type, PyObject *const *args,
+    Py_ssize_t nargs, Py_ssize_t nkw, PyObject *kwargs, PyObject *kwnames)
 {
     PyObject *return_value = NULL;
     #if defined(Py_BUILD_CORE) && !defined(Py_BUILD_CORE_MODULE)
@@ -910,12 +911,11 @@ dec_new(PyTypeObject *type, PyObject *args, PyObject *kwargs)
     #undef KWTUPLE
     PyObject *argsbuf[2];
     PyObject * const *fastargs;
-    Py_ssize_t nargs = PyTuple_GET_SIZE(args);
-    Py_ssize_t noptargs = nargs + (kwargs ? PyDict_GET_SIZE(kwargs) : 0) - 0;
+    Py_ssize_t noptargs = nargs + nkw - 0;
     PyObject *value = NULL;
     PyObject *context = Py_None;
 
-    fastargs = _PyArg_UnpackKeywords(_PyTuple_CAST(args)->ob_item, nargs, kwargs, NULL, &_parser,
+    fastargs = _PyArg_UnpackKeywords(args, nargs, kwargs, kwnames, &_parser,
             /*minpos*/ 0, /*maxpos*/ 2, /*minkw*/ 0, /*varpos*/ 0, argsbuf);
     if (!fastargs) {
         goto exit;
@@ -937,6 +937,47 @@ dec_new(PyTypeObject *type, PyObject *args, PyObject *kwargs)
     return return_value;
 }
 
+static PyObject *
+dec_new(PyTypeObject *type, PyObject *args, PyObject *kwargs)
+{
+    return dec_new_helper(type, _PyTuple_CAST(args)->ob_item,
+        PyTuple_GET_SIZE(args),
+        kwargs ? PyDict_GET_SIZE(kwargs) : 0,
+        kwargs, NULL);
+}
+
+static PyObject *
+dec_vectorcall(PyObject *type, PyObject *const *args,
+    size_t nargsf, PyObject *kwnames)
+{
+    PyObject *return_value = NULL;
+    Py_ssize_t nargs = PyVectorcall_NARGS(nargsf);
+    PyObject *value = NULL;
+    PyObject *context = Py_None;
+
+    assert(_PyType_CAST(type)->tp_new == dec_new);
+    /* Make sure the type object is immutable: the generated
+     * vectorcall doesn't deal e.g. with users reassigning __init__. */
+    assert(PyType_HasFeature(_PyType_CAST(type), Py_TPFLAGS_IMMUTABLETYPE));
+    if (kwnames != NULL || nargs > 2) {
+        return dec_new_helper(_PyType_CAST(type), args, nargs,
+            kwnames ? PyTuple_GET_SIZE(kwnames) : 0,
+            NULL, kwnames);
+    }
+    if (nargs < 1) {
+        goto skip_optional;
+    }
+    value = args[0];
+    if (nargs < 2) {
+        goto skip_optional;
+    }
+    context = args[1];
+skip_optional:
+    return_value = dec_new_impl(_PyType_CAST(type), value, context);
+
+    return return_value;
+}
+
 PyDoc_STRVAR(_decimal_Context_create_decimal__doc__,
 "create_decimal($self, num=\'0\', /)\n"
 "--\n"
@@ -7100,4 +7141,4 @@ _decimal_Context_same_quantum(PyObject *context, PyTypeObject *cls, PyObject *co
 #ifndef _DECIMAL_CONTEXT_APPLY_METHODDEF
     #define _DECIMAL_CONTEXT_APPLY_METHODDEF
 #endif /* !defined(_DECIMAL_CONTEXT_APPLY_METHODDEF) */
-/*[clinic end generated code: output=718b1f6c20412350 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=65782a3bf40cc49f input=a9049054013a1b77]*/
diff --git a/Modules/clinic/_testclinic.c.h b/Modules/clinic/_testclinic.c.h
index c3bf217a9e7b7b..4b9e5d2791d536 100644
--- a/Modules/clinic/_testclinic.c.h
+++ b/Modules/clinic/_testclinic.c.h
@@ -5030,7 +5030,7 @@ vc_plain_vectorcall(PyObject *type, PyObject *const *args,
     Py_ssize_t nargs = PyVectorcall_NARGS(nargsf);
     PyObject *a = Py_None;
 
-    assert(Py_Is(_PyType_CAST(type), &VcNew_Type));
+    assert(_PyType_CAST(type)->tp_new == vc_plain_new);
     /* Make sure the type object is immutable: the generated
      * vectorcall doesn't deal e.g. with users reassigning __init__. */
     assert(PyType_HasFeature(_PyType_CAST(type), Py_TPFLAGS_IMMUTABLETYPE));
@@ -5129,7 +5129,7 @@ vc_posorkw_vectorcall(PyObject *type, PyObject *const *args,
     PyObject *a;
     PyObject *b = Py_None;
 
-    assert(Py_Is(_PyType_CAST(type), &VcInit_Type));
+    assert(_PyType_CAST(type)->tp_init == vc_posorkw_init);
     /* Make sure the type object is immutable: the generated
      * vectorcall doesn't deal e.g. with users reassigning __init__. */
     assert(PyType_HasFeature(_PyType_CAST(type), Py_TPFLAGS_IMMUTABLETYPE));
@@ -5248,7 +5248,7 @@ vc_base_vectorcall(PyObject *type, PyObject *const *args,
     PyObject *a;
     PyObject *b = Py_None;
 
-    assert(Py_Is(_PyType_CAST(type), &VcNewBase_Type));
+    assert(_PyType_CAST(type)->tp_new == vc_base_new);
     /* Make sure the type object is immutable: the generated
      * vectorcall doesn't deal e.g. with users reassigning __init__. */
     assert(PyType_HasFeature(_PyType_CAST(type), Py_TPFLAGS_IMMUTABLETYPE));
@@ -5341,7 +5341,7 @@ vc_kwonly_vectorcall(PyObject *type, PyObject *const *args,
 {
     Py_ssize_t nargs = PyVectorcall_NARGS(nargsf);
 
-    assert(Py_Is(_PyType_CAST(type), &VcKwOnly_Type));
+    assert(_PyType_CAST(type)->tp_new == vc_kwonly_new);
     /* Make sure the type object is immutable: the generated
      * vectorcall doesn't deal e.g. with users reassigning __init__. */
     assert(PyType_HasFeature(_PyType_CAST(type), Py_TPFLAGS_IMMUTABLETYPE));
@@ -5349,4 +5349,4 @@ vc_kwonly_vectorcall(PyObject *type, PyObject *const *args,
         kwnames ? PyTuple_GET_SIZE(kwnames) : 0,
         NULL, kwnames);
 }
-/*[clinic end generated code: output=8a219f606f1296ac input=a9049054013a1b77]*/
+/*[clinic end generated code: output=31a229ecc8e80427 input=a9049054013a1b77]*/
diff --git a/Objects/clinic/enumobject.c.h b/Objects/clinic/enumobject.c.h
index 26b1801cb7312e..9b8a25a60b571e 100644
--- a/Objects/clinic/enumobject.c.h
+++ b/Objects/clinic/enumobject.c.h
@@ -99,7 +99,7 @@ enum_vectorcall(PyObject *type, PyObject *const *args,
     PyObject *iterable;
     PyObject *start = 0;
 
-    assert(Py_Is(_PyType_CAST(type), &PyEnum_Type));
+    assert(_PyType_CAST(type)->tp_new == enum_new);
     /* Make sure the type object is immutable: the generated
      * vectorcall doesn't deal e.g. with users reassigning __init__. */
     assert(PyType_HasFeature(_PyType_CAST(type), Py_TPFLAGS_IMMUTABLETYPE));
@@ -157,7 +157,7 @@ reversed_vectorcall(PyObject *type, PyObject *const *args,
     Py_ssize_t nargs = PyVectorcall_NARGS(nargsf);
     PyObject *seq;
 
-    assert(Py_Is(_PyType_CAST(type), &PyReversed_Type));
+    assert(_PyType_CAST(type)->tp_new == reversed_new);
     /* Make sure the type object is immutable: the generated
      * vectorcall doesn't deal e.g. with users reassigning __init__. */
     assert(PyType_HasFeature(_PyType_CAST(type), Py_TPFLAGS_IMMUTABLETYPE));
@@ -173,4 +173,4 @@ reversed_vectorcall(PyObject *type, PyObject *const *args,
 exit:
     return return_value;
 }
-/*[clinic end generated code: output=d0c066334eeb3b17 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=b97e8b89ca97ba64 input=a9049054013a1b77]*/
diff --git a/Objects/clinic/tupleobject.c.h b/Objects/clinic/tupleobject.c.h
index 5e136b2d1cdfdf..9d6a3edf60bb24 100644
--- a/Objects/clinic/tupleobject.c.h
+++ b/Objects/clinic/tupleobject.c.h
@@ -119,7 +119,7 @@ tuple_vectorcall(PyObject *type, PyObject *const *args,
     Py_ssize_t nargs = PyVectorcall_NARGS(nargsf);
     PyObject *iterable = NULL;
 
-    assert(Py_Is(_PyType_CAST(type), &PyTuple_Type));
+    assert(_PyType_CAST(type)->tp_new == tuple_new);
     /* Make sure the type object is immutable: the generated
      * vectorcall doesn't deal e.g. with users reassigning __init__. */
     assert(PyType_HasFeature(_PyType_CAST(type), Py_TPFLAGS_IMMUTABLETYPE));
@@ -156,4 +156,4 @@ tuple___getnewargs__(PyObject *self, PyObject *Py_UNUSED(ignored))
 {
     return tuple___getnewargs___impl((PyTupleObject *)self);
 }
-/*[clinic end generated code: output=69cab12f1ecb03e9 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=1bc2bfc233992933 input=a9049054013a1b77]*/
diff --git a/Tools/clinic/libclinic/dsl_parser.py b/Tools/clinic/libclinic/dsl_parser.py
index a798fac4f3fd09..ba3345dadecc97 100644
--- a/Tools/clinic/libclinic/dsl_parser.py
+++ b/Tools/clinic/libclinic/dsl_parser.py
@@ -639,11 +639,6 @@ def normalize_function_kind(self, fullname: str) -> None:
             if not self.kind.new_or_init:
                 fail("@vectorcall can only be used with __init__ and __new__ "
                      "methods currently")
-            # Guaranteed by the __new__ / __init__ checks above.
-            assert cls is not None
-            if not cls.type_object:
-                fail(f"@vectorcall requires the type object of {cls.name!r}, "
-                     f"which was declared without one")
 
     def resolve_return_converter(
         self, full_name: str, forced_converter: str
diff --git a/Tools/clinic/libclinic/parse_args.py b/Tools/clinic/libclinic/parse_args.py
index 4caab253fe32cc..a73e8a3d1fe060 100644
--- a/Tools/clinic/libclinic/parse_args.py
+++ b/Tools/clinic/libclinic/parse_args.py
@@ -6,7 +6,7 @@
 from libclinic.function import (
     Function, Parameter, ParamTuple,
     count_required, group_to_variable_name, permute_optional_groups,
-    GETTER, SETTER, SETTER_AND_DELETER, METHOD_INIT,
+    GETTER, SETTER, SETTER_AND_DELETER, METHOD_INIT, METHOD_NEW,
     ACCESSORS, SETTERS)
 from libclinic.converter import CConverter
 from libclinic.converters import (
@@ -1537,19 +1537,22 @@ def create_template_dict(self) -> dict[str, str]:
         return d2
 
     def _vectorcall_type_check(self) -> list[str]:
-        """Assert `type` is the one type this vectorcall was generated for.
+        """Check dispatch function hasn't changed.
 
-        The generated code is only correct for that type: __init__ calls
-        tp_new with no arguments, then the impl.  tp_vectorcall is not
-        inherited, so subclasses never reach it; the assert catches C code
-        installing the function on a second type.
+        The generated code is only correct for a type whose tp_new / tp_init is
+        the parser this vectorcall shadows.
         """
         func = self.func
-        # The DSL parser rejects @vectorcall without a class and type object.
-        assert func.cls is not None
-        assert func.cls.type_object
+        if func.kind is METHOD_INIT:
+            check = f"_PyType_CAST(type)->tp_init == {func.c_basename}"
+        elif func.kind is METHOD_NEW:
+            check = f"_PyType_CAST(type)->tp_new == {func.c_basename}"
+        else:
+            raise AssertionError(
+                f"Unhandled function kind for vectorcall: {func.kind!r}"
+            )
         return [libclinic.normalize_snippet(f"""
-            assert(Py_Is(_PyType_CAST(type), {func.cls.type_object}));
+            assert({check});
             /* Make sure the type object is immutable: the generated
              * vectorcall doesn't deal e.g. with users reassigning __init__. */
             assert(PyType_HasFeature(_PyType_CAST(type), Py_TPFLAGS_IMMUTABLETYPE));
@@ -1689,6 +1692,23 @@ def parse_vectorcall_pos_or_kw(self) -> None:
         parser_code.extend(self._vectorcall_positional(arity_checked=True))
         self.vectorcall_body(*parser_code)
 
+    def parse_vectorcall_no_args(self) -> None:
+        """No keyword or positional arguments."""
+        parser_code = self._vectorcall_type_check()
+        self.codegen.add_include('pycore_modsupport.h',
+                                 '_PyArg_NoKwnames()')
+        parser_code.append(libclinic.normalize_snippet("""
+            if (nargs) {{
+                PyErr_SetString(PyExc_TypeError,
+                                "{name}() takes no positional arguments");
+                goto exit;
+            }}
+            if (!_PyArg_NoKwnames("{name}", kwnames)) {{
+                goto exit;
+            }}
+            """, indent=4))
+        self.vectorcall_body(*parser_code)
+
     def parse_vectorcall(self) -> None:
         """Generate the vectorcall entry point for __new__ / __init__.
 
@@ -1696,11 +1716,11 @@ def parse_vectorcall(self) -> None:
         """
         # Branches ordered to mirror parse_args().  The DSL parser rejects
         # @vectorcall with optional groups, and METH_O never applies to
-        # __new__/__init__. They always have arguments.
+        # __new__/__init__.
         assert not self.has_option_groups()
         assert not self.use_meth_o()
         if not self.parameters and not self.varpos and not self.var_keyword:
-            raise NotImplementedError("No argument vectorcall")
+            self.parse_vectorcall_no_args()
         elif self.var_keyword is not None:
             self.parse_vectorcall_kw_required()
         elif self.pos_only == len(self.parameters):