ANTs: DenoiseImage is unreasonably slow

Running:

DenoiseImage -d 3 -i input.nii.gz -n Rician -o denoise.nii.gz --verbose

Seems to take an excessive amount of time.

In the meantime I can do:

> nii2mnc input.nii.gz input.mnc
> minc_anlm --rician input.mnc denoise.mnc
> mnc2nii denoise.mnc denoise.nii.gz

While DenoiseImage makes about 5% progress, sharing the same CPUs.

All the MINC commands are single threaded to top it off.

I think there may be a very significant bottleneck somewhere.

Square difference map between DenoiseImage and minc_anlm: