### 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)

bound_limit[axis_n2] = int(Math::ceil(bounds.size[axis_n2] / subdiv_cell_size));
			
			bounds.size[axis_n1] = bound_limit[axis_n1] * subdiv_cell_size;
			bounds.size[axis_n2] = bound_limit[axis_n2] * subdiv_cell_size;
		}
		GenProbesOctree octree;
		octree.size = subdiv;
		for (int i = 0; i < mesh_data.size(); i++) {
			if (p_bake_step) {
				float p = (float)(i) / mesh_data.size();
				p_bake_step(0.3 + p * 0.1, vformat(RTR("Creating probes from mesh %d/%d"), i, mesh_data.size()), p_bake_userdata, false);
			}
			for (int j = 0; j < mesh_data[i].points.size(); j += 3) {
				Vector3 points[3] = { mesh_data[i].points[j + 0] - bounds.position, mesh_data[i].points[j + 1] - bounds.position, mesh_data[i].points[j + 2] - bounds.position };
				_plot_triangle_into_octree(&octree, subdiv_cell_size, points);
			}
		}
		LocalVector<Vector3> new_probe_positions;
		HashMap<Vector3i, bool> positions_used;
		for (uint32_t i = 0; i < 8; i++) { 
			Vector3i pos;
			if (i & 1) {
				pos.x += bound_limit.x;
			}
			if (i & 2) {
				pos.y += bound_limit.y;
			}
			if (i & 4) {
				pos.z += bound_limit.z;
			}