### 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 = get_global_transform().affine_inverse() * mi->get_global_transform();
				mf.node_path = get_path_to(mi);
				mf.subindex = -1;
				mf.mesh = mesh;
				static const int lightmap_scale[GeometryInstance3D::LIGHTMAP_SCALE_MAX] = { 1, 2, 4, 8 };
				mf.lightmap_scale = lightmap_scale[mi->get_lightmap_scale()];
				Ref<Material> all_override = mi->get_material_override();
				for (int i = 0; i < mesh->get_surface_count(); i++) {
					if (all_override.is_valid()) {
						mf.overrides.push_back(all_override);
					} else {
						mf.overrides.push_back(mi->get_surface_override_material(i));
					}
				}
				meshes.push_back(mf);
			}
		}
	}
	Node3D *s = Object::cast_to<Node3D>(p_at_node);
	if (!mi && s) {
		Array bmeshes = p_at_node->call("get_bake_bmeshes");
		if (bmeshes.size() && (bmeshes.size() & 1) == 0) {
			Transform3D xf = get_global_transform().affine_inverse() * s->get_global_transform();
			for (int i = 0; i < bmeshes.size(); i += 2) {
				Ref<Mesh> mesh = bmeshes[i];
				if (!mesh.is_valid()) {
					continue;
				}
				MeshesFound mf;
				Transform3D mesh_xf = bmeshes[i + 1];