/tmp $  yes aaaaaaaaaaaaaaa | head -131072 > f
/tmp $ time LC_CTYPE=fr_FR.UTF-8 wc f >/dev/null
LC_CTYPE=fr_FR.UTF-8 wc f > /dev/null  0,40s user 0,01s system 89% cpu 0,457 total
/tmp $ time LC_CTYPE=fr_FR wc f >/dev/null
LC_CTYPE=fr_FR wc f > /dev/null  0,14s user 0,00s system 97% cpu 0,153 total
/tmp $ time LC_CTYPE=fr_FR.UTF-8 grep "." f >/dev/null
LC_CTYPE=fr_FR.UTF-8 grep --color "." f > /dev/null  252,47s user 0,16s system 95% cpu 4:25,37 total
/tmp $ time LC_CTYPE=fr_FR grep "." f >/dev/null
LC_CTYPE=fr_FR grep --color "." f > /dev/null  0,05s user 0,00s system 91% cpu 0,061 total