And on a somewhat related note /bin/sh is significantly faster than bash when it is not an old solaris (before opensolaris)/irix or similar machine, say, hpux. :)

That is, when /bin/bash is dash or a modern (k)sh it is actually faster than bash, significantly so in the case of dash (it saves bout 20s or so on the 2.5 minute configure time on my computer).

But knowing if that is the case is rather hard. Using readlink seems to work on openindiana and at least my linux, I guess:

pike-git:/gitroot/pike.git# ls -l /bin/sh lrwxrwxrwx 1 root root 9 Jan 10 2012 /bin/sh -> i86/ksh93 pike-git:/gitroot/pike.git# uname -a SunOS pike-git 5.11 oi_151a i86pc i386 i86pc Solaris

Ω leopard$ ls -l /bin/sh 0 lrwxrwxrwx 1 root root 4 feb 19 2014 /bin/sh -> dash*

Personally I think it would be much better to just use the default shell, and let the user set CONFIGURE_SHELL to override that.

Anyway, the -norc option should be checked for if we keep the current code, yes.

No. I do know that the SunOS 4 shell is very slow when you have a lot of variables, however, due to a fixed hashtable size for them.

Unless that has changed it is probably still significantly slower than /bin/bash.

Not externally.