perf: use practical default buffer size for array file writing

Author: Copilot

src/__init__.pyi

@@ -204,7 +204,7 @@ def write_array_to_file(
         __file: tp.IO[bytes],
         *,
         fortran_order: bool = False,
-        buffersize: int = 1,
+        buffersize: int = 8192,
         ) -> None: ...
 
 def first_true_1d(__array: np.ndarray, *, forward: bool) -> int: ...

src/methods.c

@@ -1116,7 +1116,7 @@ write_array_to_file(PyObject *Py_UNUSED(m), PyObject *args, PyObject *kwargs)
     PyObject *a;
     PyObject *file;
     int fortran_order = 0;
-    npy_intp buffersize = 1;
+    npy_intp buffersize = 8192;
     if (!PyArg_ParseTupleAndKeywords(args, kwargs,
             "OO|pn:write_array_to_file", write_array_to_file_kwarg_names,
             &a,