bug#31138: Native json slower than json.el

[Andy Moreton]

On Tue 23 Apr 2019, Eli Zaretskii wrote:

>> Cc: sebastien@chapu.is, yyoncho@gmail.com, 31138@debbugs.gnu.org
>> From: Dmitry Gutov <dgutov@yandex.ru>
>> Date: Tue, 23 Apr 2019 14:52:21 +0300
>> 
>> I wonder if having this optimization built-in in
>> decode-coding-string or thereabouts could give us performance gains
>> somewhere else as well.
>
> I thought about this.  It could make sense to have a UTF-8 specific
> function to encode and decode strings.  With encodings other than
> UTF-8 it becomes trickier, and probably likewise with buffer text,
> where we need to take the gap into account.
>
> What applications do we have where en/decoding strings has critical
> effect on performance?

One possible candidate is the LSP packages from ELPA/MELPA (eglot,
lsp-mode, etc) which use JSON-RPC to communicate with the external
language servers. Their interactive performance may be sensitive to JSON
overheads.

I don't yet use these tools, so perhaps someone who does can indicate if
faster JSON handling is important for these tools.

    AndyM