bug#28535: 25.2; Composed charater colon slows down Emacs performance while you in buffer with this character

[Oleksandr Gavenko]

On Thu, Sep 21, 2017 at 7:50 PM, Eli Zaretskii <eliz@gnu.org> wrote:

> From: Oleksandr Gavenko <gavenkoa@gmail.com>
> Date: Thu, 21 Sep 2017 19:12:25 +0300
> Cc: 28535@debbugs.gnu.org
>
> With:
>
> (setq inhibit-compacting-font-caches t)
>
> redisplay lags was disappeared on cursor moves.

Great, then I guess this bug can be closed?

Yes. Though I prefer to set:

(set-fontset-font nil 'symbol "DejaVu Sans Mono-10:antialias=none")

Emacs font fallback mechanism started to pick "DejaVu Sans Mono" even when special characters is defined to be displayed with Symbola.

> Is it possible to adjust font choosing preference to try well known fonts (like DejaVu) before falling to ugly and
> buggy MS Gothic? So other Emacs users will have less problems on Windows .

We already do that by default, but we prefer Symbola, as its coverage
is much better.

If you want to use DejaVu Sans Mono instead, you can customize your
fontset accordingly, see fontset.el for examples of how to do that.

OK. It seems a bit complicated to configure too many character regions. As I wrote above Emacs somehow started to prefer "DejaVu Sans Mono" as fallback font and I don't need to do anything else for now.

But it is better to install necessary fonts. At least I know where to search for spec.

For example it is very surprising to see specific font for drawing boxes:

  ;; Box Drawing and Block Elements
  (set-fontset-font "fontset-default" '(#x2500 . #x259F)
                    '("FreeMono" . "iso10646-1") nil 'prepend)

Thanks for support!