### 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)

indices_over.clear();
		for (uint32_t i = 0; i < p_simplex_indices.size(); i++) {
			if (i == min_d_idx) {
				continue;
			}
			indices_over.push_back(p_simplex_indices[i]);
		}
	}
	BSPNode node;
	node.plane = best_plane;
	if (indices_under.size() == 0) {
		
		node.under = BSPNode::EMPTY_LEAF;
	} else if (indices_under.size() == 1) {
		node.under = -(indices_under[0] + 1);
	} else {
		node.under = _compute_bsp_tree(p_points, p_planes, planes_tested, p_simplices, indices_under, bsp_nodes);
	}
	if (indices_over.size() == 0) {
		
		node.over = BSPNode::EMPTY_LEAF;
	} else if (indices_over.size() == 1) {
		node.over = -(indices_over[0] + 1);
	} else {
		node.over = _compute_bsp_tree(p_points, p_planes, planes_tested, p_simplices, indices_over, bsp_nodes);
	}
	bsp_nodes[node_index] = node;
	return node_index;
}
bool LightmapGI::_lightmap_bake_step_function(float p_completion, const String &p_text, void *ud, bool p_refresh) {