Re: Display slowness that is painful

[Kenichi Handa <handa@m17n.org>]

In article <je7j8ct3ss.fsf@sykes.suse.de>, Andreas Schwab <schwab@suse.de> writes:

> Apparently the conversion to multibyte is broken in some way.  In the
> normal case, when unibyte-display-via-language-environment is nil, no
> non-ascii character are ever used for display, so it works as expected.

I found what is wrong.  There are two problems related to
this bug.

At first, when running on a terminal, produce_glyphs is
called instead of x_produce_glyphs, but
unibyte-display-via-language-environment is handled only in
x_produce_glyphs.  So, I've just installed a fix of this
problem.  It at least fixes messing up of display as far as
your terminal and Emacs agree with terminal coding system.

Next, even in utf-8 environment, on displaying, emacs
converts unibyte characters of the range 0xA0..0xFF to some
multibyte characters if
unibyte-display-via-language-environment is non-nil.
Theoretically, as utf-8 doesn't use single byte for
non-ASCII characters, such a conversion should not be done.
But, that conversion has been done for many (7 or more)
years, and now is not a good time to change that code.

---
Kenichi Handa
handa@m17n.org