bug#24523: Base64 images makes Emacs slow

bug#24523: Base64 images makes Emacs slow

[Andreas Nilsson]

Hi.

When developing Javascript with base64 images in the code Emacs becomes
slow and laggy, it takes several seconds for a character to input in
the buffer with such an image string in it.

I have tried emacs -Q with no mode loaded and the lag is still there,
what should I do?

Thanks.

Andreas.

bug#24523: Base64 images makes Emacs slow

[Eli Zaretskii]

> Date: Sat, 24 Sep 2016 07:37:39 +0200
> From: Andreas Nilsson <an@bahnhof.se>
> 
> When developing Javascript with base64 images in the code Emacs becomes
> slow and laggy, it takes several seconds for a character to input in
> the buffer with such an image string in it.
> 
> I have tried emacs -Q with no mode loaded and the lag is still there,
> what should I do?

Report the details, please.  Ideally, post a recipe, starting with
"emacs -Q" and loading the necessary support libraries, then include
whatever commands are needed to demonstrate the slowness.  Attach
image files needed to reproduce the problem.  Also, include the
details of your platform (if you use report-emacs-bug, it will do that
for you).

Thanks.

bug#24523: Base64 images makes Emacs slow

[Andreas Nilsson]

Den Sat, 24 Sep 2016 09:53:57 +0300
skrev Re: bug#24523: Base64 images makes Emacs slow:

> > Date: Sat, 24 Sep 2016 07:37:39 +0200
> > From: Andreas Nilsson <an@bahnhof.se>
> > 
> > When developing Javascript with base64 images in the code Emacs
> > becomes slow and laggy, it takes several seconds for a character to
> > input in the buffer with such an image string in it.
> > 
> > I have tried emacs -Q with no mode loaded and the lag is still
> > there, what should I do?  
> 
> Report the details, please.  Ideally, post a recipe, starting with
> "emacs -Q" and loading the necessary support libraries, then include
> whatever commands are needed to demonstrate the slowness.  Attach
> image files needed to reproduce the problem.  Also, include the
> details of your platform (if you use report-emacs-bug, it will do that
> for you).
> 
> Thanks.

1. emacs -Q
2. Visit https://www.base64-image.de/ and "click here" select an image
(I selected a ~200kB one)
3. Click "show code" and copy paste the string you get into *scratch*.
4. Now try C-v and M-v as well as type some characters, this is the
point where it lags.

My platforms are Windows 10 and Arch Linux, happens on both. Latest
stable Emacs 25.1.1. Specifically on Arch I use x86_64 with GTK+
3.20.9, if that is of interest.

Thanks.

bug#24523: Base64 images makes Emacs slow

[Eli Zaretskii]

merge 24523 13675
thanks

> Date: Sat, 24 Sep 2016 11:09:01 +0200
> From: Andreas Nilsson <an@bahnhof.se>
> Cc: 24523@debbugs.gnu.org
> 
> 1. emacs -Q
> 2. Visit https://www.base64-image.de/ and "click here" select an image
> (I selected a ~200kB one)
> 3. Click "show code" and copy paste the string you get into *scratch*.
> 4. Now try C-v and M-v as well as type some characters, this is the
> point where it lags.

This creates a single physical line whose length is 280K characters.
It is a known limitation of the Emacs display engine that it's very
slow with such long lines.  See bug #13675.