RE: Performance problems (CPU 100%) with NULs in files

[Ludwig, Mark]

> From: Eli Zaretskii
> Subject: Re: Performance problems (CPU 100%) with NULs in files
> 
> > From: "Ludwig, Mark" <ludwig.mark@siemens.com>
> > Thread-Topic: Performance problems (CPU 100%) with NULs in files
> > Date: Wed, 21 Sep 2011 21:08:42 +0000
> >
> > What happens is that as I scroll through the file, when the NULs are
> visible, Emacs gets into some intensive processing for a long time
> (minutes, sometimes!).  It eventually unwinds and repaints the display,
> but any movement of point sends it into this loop again.  I have found
> that M-< or M-> will quickly reposition away from the problem (assuming
> the beginning and/or end of the file do not contain NULs).  Most other
> movement operations send it into the loop.
> 
> Does it help to visit such files without code conversions, i.e.
> 
>   M-x find-file-literally RET FILENAME RET
> 
> ?

No, it doesn't, but when doing this, I noticed that something else that happens 
is that the displayed line number changes to "??" when point gets into the 
NULs.  I turned off line-number-mode, but that had no effect either.  (I could 
imagine the code would waste a lot of time looking for end-of-line characters 
in those NULs....)

> If not, please file a bug report and attach to it an example file that
> causes this slowdown.

As soon as I get a minimal test case that shows the problem, I will.

Thanks,

Mark