bug#22519: 25.1.50; Emacs gets stuck while doing incremental search forward

[Eli Zaretskii <eliz@gnu.org>]

> From: vincent.belaiche@gmail.com (Vincent Belaïche)
> Cc: Vincent Belaïche <vincent.belaiche@gmail.com> ,
>  22519@debbugs.gnu.org
> Date: Tue, 15 Mar 2016 14:28:18 +0100
> 
> Ok, I decided to make some test bench (herein attached).
> 
> I get the following interaction:
> 
>  $ ./emacs-bug22519.sh --fundamental no
> -| mode: normal
> -| latin-9=(0.588 5 0.031999999999999994)
> -| utf-8=(111.257 146 1.3299999999999979)
>  $ ./emacs-bug22519.sh --fundamental yes
> -| mode: fundamental
> -| latin-9=(0.209 0 0.0)
> -| utf-8=(95.442 129 1.121)
> 
> As you see, in normal mode utf-8 is 189 times slower than latin-9, and
> in fundamental mode, it is 456 times slower.

My results are in stark contrast to yours:

 . with the current emacs-25 branch, an unoptimized build:

    $ ./emacs-bug22519.sh --fundamental no
    mode: normal
    latin-9=(5.0 5 0.10899999999999999)
    utf-8=(10.14 13 0.44)
    $ ./emacs-bug22519.sh --fundamental yes
    mode: fundamental
    latin-9=(0.359 0 0.0)
    utf-8=(2.938 4 0.126)

 . with Emacs 25.0.92 pretest, compiled with -Og:

    $ ./emacs-bug22519.sh --fundamental no
    mode: normal
    latin-9=(0.64 5 0.046)
    utf-8=(1.953 13 0.156)
    $ ./emacs-bug22519.sh --fundamental yes
    mode: fundamental
    latin-9=(0.109 0 0.0)
    utf-8=(0.984 4 0.062)

So while there is some slowdown when showing these symbols (which
could be due to the need to load the necessary font), the slowdown is
nowhere as dramatic as on your system.

IOW, I still cannot reproduce the problem on my system.  I suspect
some issue with your font configuration, but that's just a guess.