GNU bug report logs - #11943
24.1.50; Emacs unusably slow when looking at large files (bidi support at fault)

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Message #11 received at 11943 <at> debbugs.gnu.org (full text, mbox):

From: Dima Kogan <dima <at> secretsauce.net>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: 11943 <at> debbugs.gnu.org
Subject: Re: bug#11943: 24.1.50;	Emacs unusably slow when looking at large
	files (bidi support at	fault)
Date: Sat, 14 Jul 2012 20:31:03 -0700

> On Sun, 15 Jul 2012 06:04:47 +0300
> Eli Zaretskii <eliz <at> gnu.org> wrote:
>
> > From: Dima Kogan <dima <at> secretsauce.net>
> > Date: Sat, 14 Jul 2012 17:50:51 -0700
> > 
> > I'm observing that when some large text files are loaded, emacs
> > slows to a crawl. As an example, I have a 14MB file open (with
> > emacs -Q). Every time I do (next-line) or (previous-line) it takes
> > a few seconds. This is a > 2GHz Core2 machine, so there's no reason
> > for this to happen. 'M-x benchmark' says that (previous-line) takes
> > >2s each time. I discovered that if I do (setq
> > >bidi-display-reordering nil) then emacs is snappy
> > again, with previous-line taking <1ms.
> > 
> > The specific file I'm using to exhibit the bug consists of many
> > repeated stanzas such as
> > 
> > =========================
> > {
> >  {2.222222,2.222222,2.222222,2.2},
> >  {-2.222222,2.222222,2.222222},
> >  {-22.222222,22.222222,2.222222}
> > },
> > =========================
> > 
> > without the =. Saving a stanza into a file called 'snippet', the
> > 14MB file can be made with
> > 
> > $ for i in `seq 17`; do cat snippet snippet > xxx; mv xxx snippet;
> > done
> 
> What is the major mode in the buffer where you see this?  I mean the
> real-life example where you bumped into this, not the 'snippet' file
> produced by the above.

fundamental-mode

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