Subject: bug#78739: 30.1; Performance issue with inline image in an org file

From: Eli Zaretskii <[email-masked]>
Date: Sat, 21 Jun 2025 10:09:17 +0300

> Date: Fri, 20 Jun 2025 19:08:51 +0000
> From: laladrik <[email-masked]>
> Cc: [email-masked], [email-masked]
> 
> > You probably need to build debug version of Emacs with no optimizations,
> > etc. -g does not save you from the code that has been optimized away by
> > the compiler
> 
> Doesn't Emacs has some code which is enabled when it's compiled without
> optimization?  Some additional checks or asserts.  Won't it affect the
> performance enough to show a false picture?

That's the --enable-checking option to the configure script.  It's
independent of optimizations, so you could use it even for an
optimized build.

However, the --enable-checking option is for the cases where we have c
rashes and other fatal errors.  It is not very useful for debugging
performance problems.

> > FWIW, I was unable to reproduce even when I disabled the use of native
> > image API (which forces Emacs to use libpng).
> 
> How do I switch between native image API and non-native?  Should I compile it
> with the flag --with-native-image-api?

Yes.  Or invoke Emacs with

  --eval "(setq-default w32-use-native-image-API nil)"

But this is only available on MS-Windows, I think.  

> > Could this be something that depends on the version of libpng?  I have 1.6.12
> > here.
> 
> Mine is 1.6.46.  Would it help to check Emacs with your version?  I guess I can
> compile everything from the source.

I think it would be an important data point, yes.

> A little off-topic.  Who should I send the messages to and who should I add to
> "Cc" when I want my message to be seen by both of you?

What you did in the message to which I'm replying is okay: reply to
one of us and have the bug number and the rest of the people CC'ed.