Hi, Cameron-

TL;DR of below is that I am not having the same performance issues on my Ubuntu 20.04, even with newest binaries and using all gzipped dsets. I think we do have some older binaries stored around, I will have to dig. But it would be better to solve this, so you don't have to use outdated code...

I assume if you run

afni_system_check.py -check_all

nothing gets flagged?

I don't see how this would be related, but I note that in July of 2020, the linux_ubuntu_16_64 binaries got bumped up to having shared object efficiency, in that libmri.so removed the degeneracy of dependencies and greatly reduced the file size of the distribution. That started at ver=20.2.03. I don't see how that could relate to this, but that was *a* big change for these binaries between the version numbers you are citing.

If I could ask about two more env vars, what are your outputs of these?

afni -no_detach -q -VAFNI_COMPRESSOR=
afni -no_detach -q -VAFNI_DONT_USE_PIGZ=

(The results on my comp for each of these is <BLANK>.)

--- my tests ---

I tested the binaries using Bootcamp dsets. Just to reduce heterogeneity, could you try the 3dROIstats commands below on the same dsets (downloadable from here, if you don't have it already:
[afni.nimh.nih.gov]
in AFNI_data6/afni/)

I just downloaded the latest binaries on my Ubuntu 20.04

Precompiled binary linux_ubuntu_16_64: Feb 25 2021 (Version AFNI_21.0.12 'Titus')

We have the same env variable output for those three:

$ afni -no_detach -quiet -VAFNI_COMPRESSOR=
<BLANK>

$ afni -no_detach -quiet -VAFNI_AUTOGZIP=
YES

$ afni -no_detach -quiet -VAFNI_NOMMAP=
<BLANK>

I ran this on the Bootcamp data (EPI has 152 vols and 2.75x2.75.3.00 mm**3 vox):

$ time ~/linux_ubuntu_16_64/3dROIstats -mask mask.auto.nii.gz epi_r1+orig.HEAD
File	Sub-brick	Mean_1  
epi_r1+orig.HEAD	0[#0]	1541.724452
epi_r1+orig.HEAD	1[#1]	1380.877077
epi_r1+orig.HEAD	2[#2]	1340.660904
epi_r1+orig.HEAD	3[#3]	1339.089622

epi_r1+orig.HEAD	148[#148]	1334.726368
epi_r1+orig.HEAD	149[#149]	1333.623429
epi_r1+orig.HEAD	150[#150]	1332.642166
epi_r1+orig.HEAD	151[#151]	1334.085370

real	0m0.103s
user	0m0.068s
sys	0m0.035s

getting good performance.

I also tried concatenating 4 of those time series together, to make a longer dset (and a gzipped one):

3dTcat -prefix LONG.nii.gz epi_r1+orig. epi_r1+orig. epi_r1+orig. epi_r1+orig.

... but even then the performance was still fine:

$ time ~/linux_ubuntu_16_64/3dROIstats -mask mask.auto.nii.gz LONG.nii.gz
File	Sub-brick	Mean_1  
LONG.nii.gz	0[#0]	1541.724452
LONG.nii.gz	1[#1]	1380.877077
LONG.nii.gz	2[#2]	1340.660904
LONG.nii.gz	3[#3]	1339.089622
.....
LONG.nii.gz	603[#147]	1334.791271
LONG.nii.gz	604[#148]	1334.726368
LONG.nii.gz	605[#149]	1333.623429
LONG.nii.gz	606[#150]	1332.642166
LONG.nii.gz	607[#151]	1334.085370

real	0m1.294s
user	0m1.154s
sys	0m0.140s

--pt