Eu não posso falar sobre o comando do Windows, mas sim, o tempo * nix lhe dará uma resposta mais precisa:
$ time du -sch /usr/local/
147M /usr/local/
147M total
real 0m2.977s
user 0m0.008s
sys 0m0.076s
De acordo com man time
, ele pode exibir (entre muitos outras coisas):
E Elapsed real (wall clock) time used by
the process, in
[hours:]minutes:seconds.
P Percentage of the CPU that this job
got. This is just user + system times
divided by the total running time. It
also prints a percentage sign.
S Total number of CPU-seconds used by the
system on behalf of the process (in
kernel mode), in seconds.
U Total number of CPU-seconds that the
process used directly (in user mode),
in seconds.
e Elapsed real (wall clock) time used by
the process, in seconds.