How can I optimize this linspace method build in Python's C API?

Today I built a linspace function in Python's C API, here is its code:

static PyObject *
linspace(PyObject * self, PyObject * args)
{
    int n, i;
    double start, end;

    if (!PyArg_ParseTuple(args, "ddi:linspace", &start, &end, &n))
        return NULL;

    if (n <= 1)
        return Py_BuildValue("[d]", end);

    double h;
    PyObject *pylist = PyList_New(n);

    h = (end - start) / (n - 1);

    for (i = 0; i < n; i++)
        PyList_SetItem(pylist, i, Py_BuildValue("d", (start + h * i)));

    return Py_BuildValue("O", pylist);
}

It behaves how I would like it to behave, however, when I benchmarked it agains NumPy's linspace it was slower by about a factor of 80.

So I have a few questions that I think may be affecting performance, but I can't seem to find help online.

• Is there a memory leak? Or am I not incrementing or decrementing any references that I should be?

• Can I do this with a C double array and then return that as a Python Object? Would this even be faster (I think it may)?

• Am I missing something? I am new to the C API and I am not confident in it yet.