Swapping with this syntax generates one more instruction than what is really needed.
``` C
  /* "sklearn/tree/_tree.pyx":1141
 * cdef inline void swap(DTYPE_t* Xf, SIZE_t* samples, SIZE_t i, SIZE_t j) nogil:
 *     # Helper for sort
 *     Xf[i], Xf[j] = Xf[j], Xf[i]             # <<<<<<<<<<<<<<
 *     samples[i], samples[j] = samples[j], samples[i]
 * 
 */
  __pyx_t_1 = (__pyx_v_Xf[__pyx_v_j]);
  __pyx_t_2 = (__pyx_v_Xf[__pyx_v_i]);
  (__pyx_v_Xf[__pyx_v_i]) = __pyx_t_1;
  (__pyx_v_Xf[__pyx_v_j]) = __pyx_t_2;
```