[lhoursquentin]

> I would be curious if mksh is also faster. ksh93 also claims great performance increases, but it is no longer (well) maintained.

mksh `printf` is not builtin, so if the script makes heavy use of it then it tends to be slower than bash.

ksh is very interesting because it has the ability to avoid spawning new processes on most command susbstitutions, making it usually much faster than all other POSIX shells.

But again this depends heavily on what the script being executed is doing, here's a highlight of what I described:

  $ time mksh -c 'for i in $(seq 1000); do printf $(printf $(printf $(printf hello))); done' > /dev/null
  
  real    0m2.121s
  user    0m1.321s
  sys     0m0.875s

  $ time ksh -c 'for i in $(seq 1000); do printf $(printf $(printf $(printf hello))); done' > /dev/null
  
  real    0m0.013s
  user    0m0.008s
  sys     0m0.005s

  $ time dash -c 'for i in $(seq 1000); do printf $(printf $(printf $(printf hello))); done' > /dev/null
  
  real    0m0.311s
  user    0m0.279s
  sys     0m0.073s
  
  $ time bash -c 'for i in $(seq 1000); do printf $(printf $(printf $(printf hello))); done' > /dev/null
  
  real    0m0.664s
  user    0m0.538s
  sys     0m0.186s