Subject: bug#56682: locked narrowing

From: Dmitry Gutov <[email-masked]>
Date: Tue, 29 Nov 2022 21:29:59 +0200

On 29/11/2022 20:19, Eli Zaretskii wrote:
>> Date: Tue, 29 Nov 2022 19:56:30 +0200
>> Cc:[email-masked], Eli Zaretskii<[email-masked]>,
>>   Stefan Monnier<[email-masked]>
>> From: Dmitry Gutov<[email-masked]>
>>
>> Look at the timings for dictionary-pp.json. After C-s eman:
>>
>> master: ~100 ms
>> ff57f30bee, or c59b8dfefa, or Emacs 28: ~20 ms
>>
>> That's the regression.
> The faster ones use a different major-mode, btw.

The old (faster) revision uses js-mode, the new one -- the optimized 
js-json-mode. I'm sure I could have made a mistake doing that 
optimization, but the behavior doesn't indicate that: the delays are 
higher near BOB and seem absent near EOB (in master/emacs-29), and they 
don't show up in the profiler in separate leaf nodes (the previous ones 
-- which I worked on optimizing -- did).

You can also copy the definition of js-json-mode to a file and evaluate 
it in the July Emacs, and use it with that file. Or enable js-mode 
instead in the emacs-29 Emacs. The measurements do not change here.