bug#74357: c-mode: Some syntactic constructs cause unreasonable typing lag

[Alan Mackenzie <acm@muc.de>]

Hello, Björn.

Thanks for such a prompt reply.

On Sat, Nov 30, 2024 at 19:04:31 +0100, Björn Lindqvist wrote:
> Hello Alan,

> I applied your patch (patch < patch.diff), then I byte-compiled the
> changed elisp files (emacs -batch -f batch-byte-compile cc-engine.el,
> emacs -batch -f batch-byte-compile cc-mode.el), and then I installed
> them over the existing .elc files. Maybe I applied the patch wrong
> because it didn't improve performance. You can find a new profiler
> report here:

> https://gist.github.com/bjourne/c715e15729c841d1f68e00499c622d77

Sorry it hasn't worked, yet.

I've had a look at that profiler report, and it seems clear that it's
profiling something without the patch applied.  In particular, the amount
of time taken by c-inside-bracelist-p is ~29% out of the 42% that
redisplay_internal is taking.  It will also account for a similar part
of the garbage collection, giving around 2/3 of the time spent just in
c-inside-bracelist-p.

The patch ought virtually to eliminate that 2/3 of run time taken by
that function, giving a speed increase of a factor of 3.

Might it be that your Emacs is still loading native compiled files
rather than the new .elc files?  Or something like that?

> -- 
> mvh/best regards Björn Lindqvist

-- 
Alan Mackenzie (Nuremberg, Germany).