### 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 side = _bsp_get_simplex_side(p_points, p_simplices, plane, index);
				if (side == -2) {
					continue; 
				} else if (side < 0) {
					under_count++;
				} else if (side > 0) {
					over_count++;
				}
			}
			if (under_count == 0 && over_count == 0) {
				continue; 
			}
			if (under_count > over_count) { 
				SWAP(under_count, over_count);
			}
			float score = 0; 
			if (over_count > 0) {
				
				score = float(under_count) / over_count;
			}
			
			
			if (score > best_plane_score) {
				best_plane = plane;
				best_plane_score = score;
			}
		}
	}
	LocalVector<int32_t> indices_over;
	LocalVector<int32_t> indices_under;