bug#31138: Native json slower than json.el

[Eli Zaretskii <eliz@gnu.org>]

> From: yyoncho <yyoncho@gmail.com>
> Date: Mon, 25 Mar 2019 21:16:53 +0200
> Cc: Sébastien Chapuis <sebastien@chapu.is>, 
> 	31138@debbugs.gnu.org
> 
> I am unable to see any difference in the performance of the json parsing in emacs -q and in my setup - it is
> still ~2 times slower.

You mean, in your setup it's twice slower than in "emacs -Q"?

And you are saying that the changes I made have no effect on the
performance?  Then what about the 100-fold slowdown you were talking
about, allegedly caused by the hooks?

> I believe that it is caused by code_convert_string .

This needs some more specific explanation, because code_convert_string
is called in both your setup and in "emacs -Q".  So it isn't
code_convert_string itself, it's something else, perhaps triggered by
code_convert_string, like those hooks I disabled.

> I compiled emacs without that call and
> there is no difference in performance in both setups and the parsing is 2 times faster than emacs -q with
> code_convert_string.

It's small wonder that removing code makes functions which called that
code work faster.  What does removing code_convert_string achieve
except showing this truism in action?

> I want to discuss the native json performance in the context of lsp-mode needs. Is it ok to do it in this thread?

It depends on what you want to discuss, exactly.

And I'm still confused regarding the performance that bothers you.  Is
the problem the two-fold slowdown relative to "emacs -Q", or is the
problem much worse slowdown in some other situation?  Is the patch I
sent useful and should be pushed, or do you no longer care about it
because it doesn't help you?

I feel that I no longer understand what problem we are trying to
solve, and that no matter what improvements I propose, the discussion
always ends up insisting that code_convert_string is the culprit.