It used to be faster to write compressed images, due to compression being faster than hard disk transfer rates. Not any more! Solid state disks are now pretty fast, which makes (single-threaded) compression the bottleneck. We are still mostly using the outdated single-threaded GunZip for compression of most of image formats.
What do you think about adding something more modern, e.g. zstd to NRRD and/or MetaImage?