bug#21028: Performance regression in revision af1a69f4d17a482c359d98c00ef86fac835b5fac (Apr 2014).

[Eli Zaretskii]

> Cc: 21028@debbugs.gnu.org
> From: Clément Pit--Claudel <clement.pit@gmail.com>
> Date: Mon, 19 Dec 2016 11:25:28 -0500
> 
> Sorry for being unclear.  It didn't make a difference in terms of 
> performance.  That is, after applying the changes, characters display just 
> the same (which is good, since characters were already displayed in the right 
> font), but performance is still bad (every redisplay takes about 5 seconds).

In "emacs -Q"?  If so, it didn't happen to me.  I tried both the Segoe
Symbol font (which nowadays includes all the Emoji, so the Emoji font
is not needed), and the Segoe Emoji one, and saw no slow-down.

So some other factor is at work here.

> > Also, using 'unicode' is gross, IMO; it's better to specify specific
> > ranges of characters you want to be displayed using the font family.
> 
> I'm not sure.  I want to use these two fonts as fallbacks — hence the append 
> and the 'unicode range.

How can an Emoji font be a fallback for the entire range of Unicode
characters?  It's not what it's for.