[[ is from ksh88 or earlier; {,} is apparently from csh.
(Funny; I could've sworn I used {} in ksh under Solaris but
apparently not!)
Your point stands though, they are bashisms for all intents and purposes on Linux.
As to speed -- well, again, I think if you want speed don't use shell. For startup you're better off redesigning the whole damn thing (cue systemd). Changing shell is like overclocking your cpu when you should be choosing a better algorithm.
(Funny; I could've sworn I used {} in ksh under Solaris but apparently not!)
Your point stands though, they are bashisms for all intents and purposes on Linux.
As to speed -- well, again, I think if you want speed don't use shell. For startup you're better off redesigning the whole damn thing (cue systemd). Changing shell is like overclocking your cpu when you should be choosing a better algorithm.