Re: Display performance degradation

[YAMAMOTO Mitsuharu]

>>>>> On Thu, 17 Dec 2009 17:42:58 +0100, Jan Dj.ANdrv <address@hidden> said:

>>> For example, if a new font is added or if /etc/font.conf is
>>> changed, Emacs must be restarted because caches prevents Emacs
>>> from noticing the change.
>> 
>> The problem of extremely slow display is the bigger problem than
>> it.
>> 

> How much is extremely, do you have figures?  I haven't noticed any change, 
> maybe it only manifests itself for certain locales.

I can notice a clear difference on Ubuntu 9.10 with some additions for
Japanese support, running on MacBook Air (the bug reporter output is
at the end).

Steps to reproduce:

  1. emacs -Q
  2. C-u C-h t j RET
  3. Keep pressing C-v

Then scrolling looks like "waving".  The font used for displaying
Japanese characters is

  xft:-unknown-VL $B%4%7%C%/(B-normal-normal-normal-*-13-*-*-*-*-0-iso10646-1
  (The above Japanese word means "Gothic")

I think it's not noticeable with the tutorial in English (C-u C-h t a
RET in Step 2).  And on some other system such as X11 on Mac OS X
10.5, I found the difference minor.

                                     YAMAMOTO Mitsuharu
                                address@hidden

In GNU Emacs 23.1.90.1 (i686-pc-linux-gnu, GTK+ Version 2.18.3)
 of 2009-12-18 on mituharu-laptop
Windowing system distributor `The X.Org Foundation', version 11.0.10604000
Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: ja_JP.UTF-8
  value of $XMODIFIERS: @im=ibus
  locale-coding-system: utf-8-unix
  default enable-multibyte-characters: t

Major mode: Lisp Interaction

Minor modes in effect:
  tooltip-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  global-auto-composition-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent input:
<help-echo> <help-echo> <help-echo> <help-echo> <help-echo> 
<help-echo> <help-echo> <help-echo> <help-echo> <menu-bar> 
<help-menu> <send-emacs-bug-report>

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.

Load-path shadows:
None found.

Features:
(shadow sort mail-extr message sendmail regexp-opt ecomplete rfc822 mml
easymenu mml-sec password-cache mm-decode mm-bodies mm-encode mailcap
mail-parse rfc2231 rfc2047 rfc2045 qp ietf-drums mailabbrev nnheader
gnus-util netrc time-date mm-util mail-prsvr gmm-utils wid-edit
mailheader canlock sha1 hex-util hashcash mail-utils emacsbug japan-util
tooltip ediff-hook vc-hooks lisp-float-type mwheel x-win x-dnd
font-setting tool-bar dnd fontset image fringe lisp-mode register page
menu-bar rfn-eshadow timer select scroll-bar mldrag mouse jit-lock
font-lock syntax facemenu font-core frame cham georgian utf-8-lang
misc-lang vietnamese tibetan thai tai-viet lao korean japanese hebrew
greek romanian slovak czech european ethiopic indian cyrillic chinese
case-table epa-hook jka-cmpr-hook help simple abbrev loaddefs button
minibuffer faces cus-face files text-properties overlay md5 base64
format env code-pages mule custom widget hashtable-print-readable
backquote make-network-process dbusbind system-font-setting
font-render-setting gtk x-toolkit x multi-tty emacs)