In that particular case, ack's performance advantage seems to arise mostly because of a bug that causes GNU grep to be terribly slow in multibyte locales: http

In that particular case, ack's performance advantage seems to arise mostly because of a bug that causes GNU grep to be terribly slow in multibyte locales: http://blog.i-no.de/archives/2008/05/07/index.html http://blog.i-no.de/archives/2008/05/07/index.html http://savannah.gnu.org/bugs/index.php?14472 http://savannah.gnu.org/bugs/index.php?14472