bug#37516: 26.3; Windows 10: slow cursor movement with Unicode characters

[Marciano Siniscalchi]

When the buffer contains Unicode characters, cursor movement is
extremely slow---nothing happens when I hit, say, C-n, for at least one
or two seconds. I noticed this because I use prettify-symbols-mode for
LaTeX documents (love it!) and unfortunately it is unusable on
Windows. Everything works 100% fine on MacOS and Linux.

This bug is related to this old discussion:

https://lists.gnu.org/archive/html/bug-gnu-emacs/2016-11/msg00471.html

Unfortunately, the bug is still present in Emacs 26.3. The work-aroound
suggested in the above post does work thankfully. Perhaps that setting
should be the default on Windows?

Thank you!



In GNU Emacs 26.3 (build 1, x86_64-w64-mingw32)
 of 2019-08-29 built on CIRROCUMULUS
Repository revision: 96dd0196c28bc36779584e47fffcca433c9309cd
Windowing system distributor 'Microsoft Corp.', version 10.0.18362
Recent messages:
Scanning section A ...
Scanning section B ...
Scanning section C ...
Scanning document... done
Automatic display of crossref information was turned on
(Shell command succeeded with no output)
Applying style hooks...done
Wrote c:/Users/msini/.emacs.d/.emacs.desktop.lock
Desktop: 1 frame, 4 buffers restored.
For information about GNU Emacs and the GNU system, type C-h C-a.

Configured using:
 'configure --without-dbus --host=x86_64-w64-mingw32
 --without-compress-install 'CFLAGS=-O2 -static -g3''

Configured features:
XPM JPEG TIFF GIF PNG RSVG SOUND NOTIFY ACL GNUTLS LIBXML2 ZLIB
TOOLKIT_SCROLL_BARS THREADS LCMS2

Important settings:
  value of $LANG: ENU
  locale-coding-system: cp1252

Major mode: LaTeX/FMPS

Minor modes in effect:
  TeX-fold-mode: t
  LaTeX-math-mode: t
  shell-dirtrack-mode: t
  global-auto-complete-mode: t
  TeX-PDF-mode: t
  TeX-source-correlate-mode: t
  reftex-mode: t
  desktop-save-mode: t
  recentf-mode: t
  delete-selection-mode: t
  cua-mode: t
  override-global-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-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
  visual-line-mode: t
  transient-mark-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message rmc puny dired dired-loaddefs
rfc822 mml mml-sec epa derived epg gnus-util rmail rmail-loaddefs
mm-decode mm-bodies mm-encode mail-parse rfc2231 mailabbrev gmm-utils
mailheader sendmail rfc2047 rfc2045 ietf-drums mm-util mail-prsvr
mail-utils elec-pair preview prv-emacs reftex-dcr bibtex reftex-ref
reftex-parse reftex-auc reftex-cite tex-fold tex-buf font-latex latex
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tex-mode compile shell auto-complete-config auto-complete popup edmacro
kmacro multiple-cursors mc-hide-unmatched-lines-mode
mc-separate-operations rectangular-region-mode mc-mark-pop mc-mark-more
thingatpt mc-cycle-cursors mc-edit-lines multiple-cursors-core rect
pcase spaceline-config spaceline-segments s spaceline subr-x powerline
powerline-separators color powerline-themes dash atom-one-dark-theme tex
crm reftex reftex-loaddefs reftex-vars cl-extra help-mode org-element
avl-tree generator org advice org-macro org-footnote org-pcomplete
pcomplete org-list org-faces org-entities noutline outline org-version
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desktop frameset recentf tree-widget wid-edit delsel cua-base
use-package use-package-ensure use-package-delight use-package-diminish
use-package-bind-key bind-key easy-mmode use-package-core finder-inf
tex-site info package easymenu epg-config url-handlers url-parse
auth-source cl-seq eieio eieio-core cl-macs eieio-loaddefs
password-cache url-vars seq byte-opt gv bytecomp byte-compile cconv
cl-loaddefs cl-lib time-date mule-util tooltip eldoc electric uniquify
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emacs)

Memory information:
((conses 16 699415 115368)
 (symbols 48 41060 2)
 (miscs 40 6220 15558)
 (strings 32 132529 4615)
 (string-bytes 1 3415178)
 (vectors 16 49471)
 (vector-slots 8 982014 20212)
 (floats 8 361 416)
 (intervals 56 32543 1239)
 (buffers 992 16))
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