bug#24938: 25.1; 25.1 slow cursor movement with Unicode on Windows

bug#24938: 25.1; 25.1 slow cursor movement with Unicode on Windows

[Peromsik, Aaron]

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Emacs 25.1 on Windows, including the new optimized build, is much

slower than Emacs 24.5 was when navigating files which contain Unicode

characters such as ▩ .  Cursor movement noticeably stutters when using

arrow keys or typing on a line which contains that character. Just try

moving the cursor along the two lines below to see the difference:



Char: ▩ (9641, #o22651, #x25a9, file ...) point=299 of 4451 (7%) column=19

Char:  (9641, #o22651, #x25a9, file ...) point=299 of 4451 (7%) column=19









In GNU Emacs 25.1.1 (x86_64-w64-mingw32)

of 2016-11-10 built on LAPHROAIG

Windowing system distributor 'Microsoft Corp.', version 6.1.7601

Configured using:

'configure --without-dbus --without-compress-install 'CFLAGS=-O2

-static''



Configured features:

XPM JPEG TIFF GIF PNG RSVG SOUND NOTIFY ACL GNUTLS LIBXML2 ZLIB

TOOLKIT_SCROLL_BARS



Important settings:

  value of $LANG: C

  locale-coding-system: cp1252



Major mode: Text



Minor modes in effect:

  midnight-mode: t

  auto-image-file-mode: t

  diff-auto-refine-mode: t

  shell-dirtrack-mode: t

  display-time-mode: t

  tooltip-mode: t

  global-eldoc-mode: t

  electric-indent-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

  auto-fill-function: do-auto-fill

  transient-mark-mode: t



Recent messages:

Loading magit-autorevert...done

Loading midnight...done

Loading paren...done

0 buffers purged

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

GNU Emacs 25.1.1 (x86_64-w64-mingw32) of 2016-11-10

d:/home/peromsik/fixes/41regp30/tha_bas_assmcut_bf02_p20/p30ntmp/std.out

Mark saved where search started [2 times]

d:/home/peromsik/fixes/41regp30/tha_bas_assmcut_bf02_p20/p30imr/std.out

Mark saved where search started [2 times]



Load-path shadows:

None found.



Features:

(shadow sort mail-extr emacsbug message format-spec rfc822 mml mml-sec

password-cache epg gnus-util mm-decode mm-bodies mm-encode mail-parse

rfc2231 mailabbrev gmm-utils mailheader sendmail rfc2047 rfc2045

ietf-drums mm-util help-fns mail-prsvr mail-utils dired-aux misearch

multi-isearch org-install esh-var esh-io esh-cmd esh-opt esh-ext

esh-proc esh-arg esh-groups eshell esh-module esh-mode esh-util

jka-compr paren midnight magit-autorevert autorevert filenotify

magit-git cl-seq crm magit-section magit-utils dash ido icomplete

image-file cus-start cus-load server ps-print ps-def lpr diff-mode

easy-mmode grep compile ediff-merg ediff-wind ediff-diff ediff-mult

ediff-help ediff-init ediff-util ediff ccase ptctags ptcsrc warnings

advice dired-x dired ptc-comment aap-autoload shell pcomplete comint

ansi-color ring cc-mode cc-fonts cc-guess cc-menus cc-cmds cc-styles

cc-align cc-engine cc-vars cc-defs time finder-inf go-mode-autoloads

info package epg-config seq byte-opt gv bytecomp byte-compile cl-extra

help-mode easymenu cconv cl-loaddefs pcase cl-lib time-date mule-util

tooltip eldoc electric uniquify ediff-hook vc-hooks lisp-float-type

mwheel dos-w32 ls-lisp disp-table w32-win w32-vars term/common-win

tool-bar dnd fontset image regexp-opt fringe tabulated-list newcomment

elisp-mode lisp-mode prog-mode register page menu-bar rfn-eshadow timer

select scroll-bar mouse jit-lock font-lock syntax facemenu font-core

frame cl-generic cham georgian utf-8-lang misc-lang vietnamese tibetan

thai tai-viet lao korean japanese eucjp-ms cp51932 hebrew greek romanian

slovak czech european ethiopic indian cyrillic chinese charscript

case-table epa-hook jka-cmpr-hook help simple abbrev minibuffer

cl-preloaded nadvice loaddefs button faces cus-face macroexp files

text-properties overlay sha1 md5 base64 format env code-pages mule

custom widget hashtable-print-readable backquote w32notify w32 multi-tty

make-network-process emacs)



Memory information:

((conses 16 255848 15149)

(symbols 56 33020 0)

(miscs 48 127 185)

(strings 32 77739 8844)

(string-bytes 1 2075782)

(vectors 16 27303)

(vector-slots 8 674830 18474)

(floats 8 473 135)

(intervals 56 1273 1083)

(buffers 976 70))



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bug#24938: 25.1; 25.1 slow cursor movement with Unicode on Windows

[Eli Zaretskii]

> From: "Peromsik, Aaron" <peromsik@ptc.com>
> Date: Sun, 13 Nov 2016 20:13:34 +0000
> 
> Emacs 25.1 on Windows, including the new optimized build, is much
> slower than Emacs 24.5 was when navigating files which contain Unicode
> characters such as ¢Ì . Cursor movement noticeably stutters when using
> arrow keys or typing on a line which contains that character. Just try
> moving the cursor along the two lines below to see the difference:
> 
> Char: ¢Ì (9641, #o22651, #x25a9, file ...) point=299 of 4451 (7%) column=19
> Char: (9641, #o22651, #x25a9, file ...) point=299 of 4451 (7%) column=19

I don't see the problem here.

I think this is another case of bug#24565.  If you can try building
the current emacs-25 branch and setting the new variable
inhibit-compacting-font-caches to non-nil, we can now for sure.

bug#24938: 25.1; 25.1 slow cursor movement with Unicode on Windows

[Peromsik, Aaron]

Yes, that's much better. Thanks!

(Though it does raise the question... how many times should font caches be compacted while the user moves the mouse across lines which are already displayed on the screen?)

bug#24938: 25.1; 25.1 slow cursor movement with Unicode on Windows

[Eli Zaretskii]

> From: "Peromsik, Aaron" <peromsik@ptc.com>
> CC: "24938@debbugs.gnu.org" <24938@debbugs.gnu.org>
> Date: Sun, 13 Nov 2016 21:43:50 +0000
> 
> Yes, that's much better. Thanks!

OK, closing.

> (Though it does raise the question... how many times should font caches be compacted while the user moves the mouse across lines which are already displayed on the screen?)

With some fonts, the cache is compacted on every GC, and GC happens
very frequently.  So in your case, the answer is probably "every
cursor movement".