### Godot version

4.0 beta 17

### System information

Windows 11, Forward+, RTX 4090

### Issue description

In the latest beta, baking LightmapGI has taken a big performance hit. The baking itself might not be the problem, it's the (Re)Importing Assets step for the `.exr` that seems to take all the time.




### Steps to reproduce

I've included a repro project to demonstrate it. Click the `LightmapGI` node and then the `Bake Lightmaps` button.

Before Beta 17:
`Done baking lightmaps in 00:00:01.`

With Beta 17 (and the latest Master branch, just in case):
`Done baking lightmaps in 00:00:08.`



### Minimal reproduction project

[lightmap-regression-repro.zip](https://github.com/godotengine/godot/files/10579835/lightmap-regression-repro.zip)

mf.xform = xf * mesh_xf;
				mf.node_path = get_path_to(s);
				mf.subindex = i / 2;
				mf.lightmap_scale = 1;
				mf.mesh = mesh;
				meshes.push_back(mf);
			}
		}
	}
	Light3D *light = Object::cast_to<Light3D>(p_at_node);
	if (light && light->get_bake_mode() != Light3D::BAKE_DISABLED) {
		LightsFound lf;
		lf.xform = get_global_transform().affine_inverse() * light->get_global_transform();
		lf.light = light;
		lights.push_back(lf);
	}
	LightmapProbe *probe = Object::cast_to<LightmapProbe>(p_at_node);
	if (probe) {
		Transform3D xf = get_global_transform().affine_inverse() * probe->get_global_transform();
		probes.push_back(xf.origin);
	}
	for (int i = 0; i < p_at_node->get_child_count(); i++) {
		Node *child = p_at_node->get_child(i);
		if (!child->get_owner()) {
			continue; 
		}
		_find_meshes_and_lights(child, meshes, lights, probes);
	}
}
int LightmapGI::_bsp_get_simplex_side(const Vector<Vector3> &p_points, const LocalVector<BSPSimplex> &p_simplices, const Plane &p_plane, uint32_t p_simplex) const {