Out of curiosity, I made a rough test.
Reading a sequence of 2200 PNG images that resulted in a 10GB volume took 3’ 25" on a 32GB laptop with a nvme drive (Using ImageStack from @pieper). Saving same volume as nrrd without compression took about 4 seconds. Flushing the cache and reloading the uncompressed 10GB NRRD into a fresh instance of Slicer took 26 seconds.