Irb loading generates 17x more open/stat system calls when a locale is set
I did just found out that when I have a locale set (e.g. cs_CZ in my case), irb does some extra finding for rb/so files which are being required. That slows down loading time and if you have many rubygems, loading can be really slow.
$ LC_ALL=cs_CZ strace irb < /dev/null 2>&1 | grep ENOENT | wc -l
$ LC_ALL=C strace irb < /dev/null 2>&1 | grep ENOENT | wc -l
$ time LC_ALL=cs_CZ irb < /dev/null
$ time LC_ALL=C irb < /dev/null
Tested on stable 1.9.3 and also on 2.0 RC1. All the same.