### 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)

Ref<Image> albedo = images[RS::BAKE_CHANNEL_ALBEDO_ALPHA];
			Ref<Image> orm = images[RS::BAKE_CHANNEL_ORM];
			
			Lightmapper::MeshData md;
			{
				Dictionary d;
				d["path"] = mf.node_path;
				if (mf.subindex >= 0) {
					d["subindex"] = mf.subindex;
				}
				md.userdata = d;
			}
			{
				if (albedo->get_format() != Image::FORMAT_RGBA8) {
					albedo->convert(Image::FORMAT_RGBA8);
				}
				if (orm->get_format() != Image::FORMAT_RGBA8) {
					orm->convert(Image::FORMAT_RGBA8);
				}
				Vector<uint8_t> albedo_alpha = albedo->get_data();
				Vector<uint8_t> orm_data = orm->get_data();
				Vector<uint8_t> albedom;
				uint32_t len = albedo_alpha.size();
				albedom.resize(len);
				const uint8_t *r_aa = albedo_alpha.ptr();
				const uint8_t *r_orm = orm_data.ptr();
				uint8_t *w_albedo = albedom.ptrw();
				for (uint32_t i = 0; i < len; i += 4) {
					w_albedo[i + 0] = uint8_t(CLAMP(float(r_aa[i + 0]) * (1.0 - float(r_orm[i + 2] / 255.0)), 0, 255));
					w_albedo[i + 1] = uint8_t(CLAMP(float(r_aa[i + 1]) * (1.0 - float(r_orm[i + 2] / 255.0)), 0, 255));