bug#14259: 24.1; global-linum-mode slows down scrolling and user input in DocView

[James Hudon <jameshudon@gmail.com>]

Hi
I'm using GNU Emacs 24.1 (emacs24 on Ubuntu 12.10)
to repro:
1. Launch emacs with "emacs -Q"
2. Open a PDF that has pages you can scroll
3. Scroll around (should be responsive)
4. Turn on `M-x global-linum-mode`
5. Ensure the global-linum-mode is enabled and now scroll around/change
pages/etc. There should be a noticeable lag that makes it very hard to
use




In GNU Emacs 24.1.1 (x86_64-pc-linux-gnu, GTK+ Version 2.24.12)
 of 2012-09-22 on batsu, modified by Debian
Windowing system distributor `The X.Org Foundation', version 11.0.11300000
Configured using:
 `configure '--build' 'x86_64-linux-gnu' '--build' 'x86_64-linux-gnu'
 '--prefix=/usr' '--sharedstatedir=/var/lib' '--libexecdir=/usr/lib'
 '--localstatedir=/var/lib' '--infodir=/usr/share/info'
 '--mandir=/usr/share/man' '--with-pop=yes'
 '--enable-locallisppath=/etc/emacs24:/etc/emacs:/usr/local/share/emacs/24.1/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/24.1/site-lisp:/usr/share/emacs/site-lisp'
 '--with-crt-dir=/usr/lib/x86_64-linux-gnu' '--with-x=yes'
 '--with-x-toolkit=gtk' '--with-toolkit-scroll-bars'
 'build_alias=x86_64-linux-gnu' 'CFLAGS=-g -O2 -fstack-protector
 --param=ssp-buffer-size=4 -Wformat -Werror=format-security -Wall -O2'
 'CPPFLAGS=-D_FORTIFY_SOURCE=2''

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: en_CA.UTF-8
  value of $XMODIFIERS: nil
  locale-coding-system: utf-8-unix
  default enable-multibyte-characters: t

Major mode: DocView

Minor modes in effect:
  global-linum-mode: t
  linum-mode: t
  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
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent input:
C-x C-f <M-backspace> <M-backspace> D o c u <tab> S 
c h o <tab> W a t <tab> w p 4 / <tab> u w <tab> u <backspace> 
w k <tab> - s e <tab> p d f <return> n p n n n p p 
<help-echo> <down-mouse-5> <mouse-5> <help-echo> <down-mouse-5> 
<mouse-5> <help-echo> <down-mouse-5> <mouse-5> <double-down-mouse-5> 
<double-mouse-5> <help-echo> <down-mouse-4> <mouse-4> 
<double-down-mouse-4> <double-mouse-4> <triple-down-mouse-4> 
<triple-mouse-4> <help-echo> <down-mouse-5> <mouse-5> 
<help-echo> <down-mouse-5> <mouse-5> <help-echo> M-x 
g l o b a l - l i <tab> <return> n <help-echo> <down-mouse-4> 
<mouse-4> <double-down-mouse-4> <double-mouse-4> <triple-down-mouse-4> 
<triple-mouse-4> <triple-down-mouse-4> <triple-mouse-4> 
<triple-down-mouse-4> <triple-mouse-4> p <down-mouse-5> 
<mouse-5> <double-down-mouse-5> <double-mouse-5> <triple-down-mouse-5> 
<triple-mouse-5> <triple-down-mouse-5> <triple-mouse-5> 
n <down-mouse-4> <mouse-4> <double-down-mouse-4> <double-mouse-4> 
<triple-down-mouse-4> <triple-mouse-4> M-x r e p o 
r t - e m <tab> <return>

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
DocView: using cached files!
Type C-c C-c to toggle between editing or viewing the document.
Loading vc-git...done
Global-Linum mode enabled

Load-path shadows:
/usr/share/emacs/24.1/site-lisp/debian-startup hides /usr/share/emacs/site-lisp/debian-startup
/usr/share/emacs/24.1/site-lisp/dictionaries-common/ispell hides /usr/share/emacs/24.1/lisp/textmodes/ispell
/usr/share/emacs/24.1/site-lisp/dictionaries-common/flyspell hides /usr/share/emacs/24.1/lisp/textmodes/flyspell

Features:
(shadow sort gnus-util mail-extr emacsbug message format-spec rfc822 mml
mml-sec mm-decode mm-bodies mm-encode mail-parse rfc2231 mailabbrev
gmm-utils mailheader sendmail rfc2047 rfc2045 ietf-drums mm-util
mail-prsvr mail-utils cus-start cus-load linum vc-git doc-view easymenu
jka-compr image-mode dired regexp-opt time-date tooltip ediff-hook
vc-hooks lisp-float-type mwheel x-win x-dnd tool-bar dnd fontset image
fringe lisp-mode register page menu-bar rfn-eshadow timer select
scroll-bar 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 minibuffer loaddefs button faces cus-face files text-properties
overlay sha1 md5 base64 format env code-pages mule custom widget
hashtable-print-readable backquote make-network-process dbusbind
dynamic-setting system-font-setting font-render-setting move-toolbar gtk
x-toolkit x multi-tty emacs)