Re: A certain unicode character makes -git Emacs eat all the CPU and become very slow.

[Po Lu]

Vladimir Nikishkin <lockywolf@gmail.com> writes:

> Okay, I have had some progress.
>
> The font that causes Emacs to misbehave is AdobeBlank, often shipped
> in the "Google Fonts" (not Google Noto) package.
>
> It does not have to be used for display, it is its presence that makes
> Emacs cog a core.
>
> That "Blank" font covers all of Unicode, but every glyph is an empty
> picture. I guess it is designed for the situations when there may be
> symbols from out of the installed range, but when displaying "tofu" is
> not desired, say, on public displays.
>
> But in any case, it is a fairly standard, widespread font. I don't
> think Emacs should behave like this in its presence.

I am hardly an expert in the font related code, but could you try to see
how many the function `ftfont_match' is called when the freeze happens,
with and without that font?

Thanks.