Subject: Re: bug#55729: 27.1; Emacs 28.1 `string-match' is five times slower than Emacs 27.1

From: Eli Zaretskii <[email-masked]>
Date: Mon, 30 May 2022 19:03:28 +0300

> Cc: [email-masked], [email-masked]
> Date: Mon, 30 May 2022 18:58:17 +0300
> From: Eli Zaretskii <[email-masked]>
> 
> > I tried your test, and the results were within a few percentages of each
> > other in 27.1 and 28.1.
> 
> With a 3GB file being inserted non-literally, there could be factors
> at work here that are entirely unrelated to processing speed.  The
> implementation of string-match basically didn't change between Emacs
> 27 and Emacs 28, AFAICT.

Here's one random thought: were both Emacs 27 and Emacs 28 compiled
with the same compiler version, and do they both use the same version
of the Standard C Library?