### 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)

for (int i = 0; i < 8; i++) {
		Vector3i pos = p_cell->offset;
		uint32_t half_size = p_cell->size / 2;
		if (i & 1) {
			pos.x += half_size;
		}
		if (i & 2) {
			pos.y += half_size;
		}
		if (i & 4) {
			pos.z += half_size;
		}
		AABB subcell;
		subcell.position = Vector3(pos) * p_cell_size;
		subcell.size = Vector3(half_size, half_size, half_size) * p_cell_size;
		if (!Geometry3D::triangle_box_overlap(subcell.get_center(), subcell.size * 0.5, p_triangle)) {
			continue;
		}
		if (p_cell->children[i] == nullptr) {
			GenProbesOctree *child = memnew(GenProbesOctree);
			child->offset = pos;
			child->size = half_size;
			p_cell->children[i] = child;
		}
		if (half_size > 1) {
			
			_plot_triangle_into_octree(p_cell->children[i], p_cell_size, p_triangle);
		}
	}
}