Subject: bug#16232: [PATCH] grep: make --ignore-case (-i) faster (sometimes 10x) in multibyte locales

From: Paul Eggert <[email-masked]>
Date: Wed, 19 Feb 2014 10:30:24 -0800

On 02/19/2014 06:22 AM, Norihiro Tanaka wrote:
> I tested performance on grep-2.17 and the version which the patch is reverted.
> Latter is 100x faster.

While we're on the topic, can someone please say why that patch was done 
as a preprocessor for the regex code?  I normally would think that the 
way to speed up regex processing is to improve dfa.c and/or the regex 
library, as that should speed up all programs that use these modules, 
not just grep.