### 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)

positions_used[pos] = true;
			Vector3 real_pos = bounds.position + Vector3(pos) * subdiv_cell_size; 
			new_probe_positions.push_back(real_pos);
		}
		
		for (int i = 0; i < 8; i++) {
			if (octree.children[i]) {
				_gen_new_positions_from_octree(octree.children[i], subdiv_cell_size, probes_found, new_probe_positions, positions_used, bounds);
			}
		}
		for (const Vector3 &position : new_probe_positions) {
			probes_found.push_back(position);
		}
	}
	
	if (p_bake_step) {
		p_bake_step(0.4, RTR("Preparing Lightmapper"), p_bake_userdata, true);
	}
	{
		for (int i = 0; i < mesh_data.size(); i++) {
			lightmapper->add_mesh(mesh_data[i]);
		}
		for (int i = 0; i < lights_found.size(); i++) {
			Light3D *light = lights_found[i].light;
			Transform3D xf = lights_found[i].xform;
			Color linear_color = light->get_color().srgb_to_linear();
			float energy = light->get_param(Light3D::PARAM_ENERGY);
			if (GLOBAL_GET("rendering/lights_and_shadows/use_physical_light_units")) {
				energy *= light->get_param(Light3D::PARAM_INTENSITY);
				linear_color *= light->get_correlated_color().srgb_to_linear();