Re: emacs rendering comparisson between emacs23 and emacs26.3

[Dmitry Gutov]

On 07.04.2020 22:22, Eli Zaretskii wrote:

> > and are likely fixable without significant redesign.
>
> Unfortunately, I'm not as optimistic as you on that one.

In any case, s-p-f is unlikely to help there. ¯\_(ツ)_/¯

> So here's the first bug report about a random slowness in CC Mode:

Thank you.

>    . visit src/w32.c on the emacs-27 branch and go to line 8747
>    . C-e DEL -- this deletes the last 'e' of "else"
>    . the following line gets immediately fontified as a function name
>    . type 'e' -- then watch how the fontification of the next line to
>      its original face takes almost 1 sec -- this is the problem

I can and can't reproduce this at the same time.

Meaning, I do see "fontification of the next line to its original face" 
take some time. But if I don't wait for it to turn black again and 
continue typing, nothing bad happens: Emacs continues reacting to input 
just as promptly, and the next line turns black soon enough.

And if I type e.g. 'e RET', or 'e SPC', the next line turns black 
seemingly instantly.

> FTR, this is in Emacs 27.0.90 built with -Og, but a -O2 compilation of
> Emacs 26.3 takes only slightly less time in this case.

'emacs -Q' and a '-Og -g3' build of 27.0.90 here.