### 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)

}
				}
				if (plane_index == -1) {
					plane_index = bsp_planes.size();
					bsp_planes.push_back(p);
				}
				bsp_simplex.planes[j] = plane_index;
				
				tetrahedrons.push_back(solved_simplices[i].points[j]);
			}
			bsp_simplex_indices.push_back(bsp_simplices.size());
			bsp_simplices.push_back(bsp_simplex);
		}
#ifdef DEBUG_SIMPLICES_AS_OBJ_FILE
		{
			Ref<FileAccess> f = FileAccess::open("res://bsp.obj", FileAccess::WRITE);
			for (uint32_t i = 0; i < bsp_simplices.size(); i++) {
				f->store_line("o Simplex" + itos(i));
				for (int j = 0; j < 4; j++) {
					f->store_line(vformat("v %f %f %f", points[bsp_simplices[i].vertices[j]].x, points[bsp_simplices[i].vertices[j]].y, points[bsp_simplices[i].vertices[j]].z));
				}
				static const int face_order[4][3] = {
					{ 1, 2, 3 },
					{ 1, 3, 4 },
					{ 1, 2, 4 },
					{ 2, 3, 4 }
				};
				for (int j = 0; j < 4; j++) {
					f->store_line(vformat("f %d %d %d", 4 * i + face_order[j][0], 4 * i + face_order[j][1], 4 * i + face_order[j][2]));
				}