# Passing first-type class jitted method is very slow

**URL:** <https://numba.discourse.group/t/passing-first-type-class-jitted-method-is-very-slow/957>\
**Category:** Numba\
**Created:** [October 12, 2021, 7:58am UTC](https://numba.discourse.group/t/passing-first-type-class-jitted-method-is-very-slow/957 "2021-10-12T07:58:38Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![duburcqa](https://yyz2.discourse-cdn.com/free1/user_avatar/numba.discourse.group/duburcqa/32/222_2.png) [@duburcqa](https://numba.discourse.group/u/duburcqa)\
**Post date:** [October 12, 2021, 7:58am UTC](https://numba.discourse.group/t/passing-first-type-class-jitted-method-is-very-slow/957/1 "2021-10-12T07:58:38Z")

</div>

Hi!

I get a 10x slowdown if I jit a jitted method instead of calling it manually directly. How is this possible ?

```auto
 >>> @nb.jit(nopython=True, nogil=True)
...: def _sum_tile_ground_impl(x: float,
...: y: float,
...: height: np.ndarray,
...: normal: np.ndarray,
...: heightmap_py_1) -> None:
...: heightmap_py_1(x, y, height, normal)
...: 

>>> %timeit _sum_tile_ground_impl(0.0, 0.0, np.array(0.0), np.zeros(3), heightmaps[0])
15.4 µs ± 75.4 ns per loop (mean ± std. dev. of 7 runs, 100000 loops each)

>>> %timeit heightmaps[0](0.0, 0.0, np.array(0.0), np.zeros(3))
1.39 µs ± 7.68 ns per loop (mean ± std. dev. of 7 runs, 1000000 loops each)

```

This is a simplified example of what I want to do. The actual implementation of `_sum_tile_ground_impl` is as follow. So that it runs signficantly slower than native python:

```auto
    @nb.jit(nopython=True, nogil=True)
    def _sum_tile_ground_impl(x: float,
                              y: float,
                              height: np.ndarray,
                              normal: np.ndarray,
                              height_buffer: np.ndarray,
                              normal_buffer: np.ndarray) -> None:
        heightmaps_py[0](x, y, height, normal)
        for heightmap_py in heightmaps_py[1:]:
            heightmap_py(x, y, height_buffer, normal_buffer)
            height += height_buffer
            normal += normal_buffer
        normal /= math.sqrt(normal[0] **2 + normal[1]** 2 + normal[0] ** 2)

```

where `heightmaps_py` is a list of jitter methodsall having the same signature and available in nonlocal scope.

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<div class="post-metadata">

**Author:** ![esc](https://yyz2.discourse-cdn.com/free1/user_avatar/numba.discourse.group/esc/32/49_2.png) [@esc](https://numba.discourse.group/u/esc)\
**Post date:** [October 13, 2021, 8:43am UTC](https://numba.discourse.group/t/passing-first-type-class-jitted-method-is-very-slow/957/2 "2021-10-13T08:43:55Z")

</div>

Is there any way you could submit a complete, runnable script so that someone can reproduce your findings?