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

[Ludwig, Mark]

I filed bug#9589 before your message.  Since you know about this sort of 
problem generally, I assume the description will make sense.

Cheers,

Mark

-----Original Message-----
From: help-gnu-emacs-bounces+ludwig.mark=siemens.com@gnu.org 
[mailto:help-gnu-emacs-bounces+ludwig.mark=siemens.com@gnu.org] On Behalf Of 
Eli Zaretskii
Sent: Saturday, September 24, 2011 1:04 AM
To: help-gnu-emacs@gnu.org
Subject: Re: Performance problems (CPU 100%) with NULs in files

> From: "Ludwig, Mark" <ludwig.mark@siemens.com>
> Date: Sat, 24 Sep 2011 00:20:24 +0000
> 
> What I have found is that the "problem" is due to a "line" of text being 
> extremely long.  In the test file I have, it is ~800,000 characters (bytes).  
> (It came to me with NULs, but I can replace those with any other printable 
> character and get the same result.)

Yes, this is a well-known case that causes the current display engine
become very slow.  IIRC, it has been like that since Emacs 21.1.

> OTOH, if you guys really think this is worth asking any developer to fix, 
> I'll file a bug report.  I don't need to send any data, because it's easy to 
> reproduce this behavior starting with an empty buffer.

Please file a bug report.  It is not unreasonable to expect the code
to be optimized in some way to cater to such use cases.

And thanks for taking your time to investigate this.