### 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)

int over = 0;
	int under = 0;
	const BSPSimplex &s = p_simplices[p_simplex];
	for (int i = 0; i < 4; i++) {
		const Vector3 v = p_points[s.vertices[i]];
		if (p_plane.has_point(v)) {
			
		} else if (p_plane.is_point_over(v)) {
			over++;
		} else {
			under++;
		}
	}
	ERR_FAIL_COND_V(under == 0 && over == 0, -2); 
	if (under == 0) {
		return 1; 
	} else if (over == 0) {
		return -1; 
	} else {
		return 0; 
	}
}
int32_t LightmapGI::_compute_bsp_tree(const Vector<Vector3> &p_points, const LocalVector<Plane> &p_planes, LocalVector<int32_t> &planes_tested, const LocalVector<BSPSimplex> &p_simplices, const LocalVector<int32_t> &p_simplex_indices, LocalVector<BSPNode> &bsp_nodes) {