That seem abysmally slow for grep. On my machine, with a 1.1G file made of 1200 ...

ambrosio on Dec 13, 2015 | parent | context | favorite | on: look(1): lines beginning with given string

That seem abysmally slow for grep. On my machine, with a 1.1G file made of 1200 copies of /usr/share/dict/words, GNU grep 2.16 takes about 1.5 seconds. Try with LC_ALL=C?