Re: emacs rendering comparisson between emacs23 and emacs26.3

[Eli Zaretskii]

> From: Dmitry Gutov <address@hidden>
> Date: Tue, 7 Apr 2020 18:04:13 +0300
> Cc: address@hidden, address@hidden, address@hidden, address@hidden,
>  address@hidden
> 
> Scenarios which are slow no matter what probably deserve a separate bug 
> report each

Agreed, let's get that ball rolling.

> and are likely fixable without significant redesign.

Unfortunately, I'm not as optimistic as you on that one.

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

  . 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

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.

(I will file a formal bug report about this if Alan wants me to.)