### 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 (index.size()) {
					facecount = index.size() / 3;
					ir = index.ptr();
				} else {
					facecount = vertices.size() / 3;
				}
				for (int j = 0; j < facecount; j++) {
					uint32_t vidx[3];
					if (ir) {
						for (int k = 0; k < 3; k++) {
							vidx[k] = ir[j * 3 + k];
						}
					} else {
						for (int k = 0; k < 3; k++) {
							vidx[k] = j * 3 + k;
						}
					}
					for (int k = 0; k < 3; k++) {
						Vector3 v = mf.xform.xform(vr[vidx[k]]);
						if (bounds == AABB()) {
							bounds.position = v;
						} else {
							bounds.expand_to(v);
						}
						md.points.push_back(v);
						md.uv2.push_back(uvr[vidx[k]]);
						md.normal.push_back(normal_xform.xform(nr[vidx[k]]).normalized());
					}
				}
			}