Linux:shell:command: speed up 'grep'

'grep' is very slow when using it in a UTF-8 mode, specially for a large text file. However, it is fast if using 'C' mode. Use the command 'locale' to check the variable of 'LC_ALL'. Then

export LC_ALL="C"

(from http://tdas.wordpress.com/2008/02/03/speed-up-grep)

I tested it. The "C" mode is faster 50 times than the regular mode!