### 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)

Array ret;
	if (light_texture.is_null() || light_texture->get_layers() == 0) {
		return ret;
	}
	Vector<Ref<Image>> images;
	for (int i = 0; i < light_texture->get_layers(); i++) {
		images.push_back(light_texture->get_layer_data(i));
	}
	int slice_count = images.size();
	int slice_width = images[0]->get_width();
	int slice_height = images[0]->get_height();
	int slices_per_texture = Image::MAX_HEIGHT / slice_height;
	int texture_count = Math::ceil(slice_count / (float)slices_per_texture);
	ret.resize(texture_count);
	String base_name = get_path().get_basename();
	int last_count = slice_count % slices_per_texture;
	for (int i = 0; i < texture_count; i++) {
		int texture_slice_count = (i == texture_count - 1 && last_count != 0) ? last_count : slices_per_texture;
		Ref<Image> texture_image = Image::create_empty(slice_width, slice_height * texture_slice_count, false, images[0]->get_format());
		for (int j = 0; j < texture_slice_count; j++) {
			texture_image->blit_rect(images[i * slices_per_texture + j], Rect2i(0, 0, slice_width, slice_height), Point2i(0, slice_height * j));
		}
		String texture_path = texture_count > 1 ? base_name + "_" + itos(i) + ".exr" : base_name + ".exr";
		Ref<ConfigFile> config;
		config.instantiate();
		if (FileAccess::exists(texture_path + ".import")) {
			config->load(texture_path + ".import");
		}