Disabling fragments, by passing the -no-fragments option to mksquashfs,
retains performance while providing reproducibility:

A) 12 core Xeon E5-2609 v3 with 16GB of ram

Without the frag deflator removal patch and with the -no-fragments option:
 real 0.900000-0.970000(0.928+/-0.023)
 user 9.470000-9.620000(9.531+/-0.046)
 sys 0.090000-0.180000(0.12+/-0.022)

B) Raspberry Pi 2 (4 core, 1GB of ram)

Without the frag deflator removal patch and with the -no-fragments
option:

 real 14.480000-14.610000(14.547+/-0.033)
 user 53.250000-53.660000(53.467+/-0.13)
 sys 2.910000-3.240000(3.056+/-0.094)

We actually see a small performance improvement. The downside here is
that the resulting squashfs image isn't as small. This particular nmap
snap increases from 5.4M to 5.8M in size. However, I suspect that the
small increase in size is negated entirely by mksquashfs producing
consistent snaps that can be accurately binary diffed for delta
upgrades. More investigation is needed to make that claim but that's my
current hunch.

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https://bugs.launchpad.net/bugs/1576763

Title:
  pi2 images generate different checksums on repeated runs

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