To reproduce, open the attached file in Emacs, and type C-x C-n. On my system Emacs uses 100% of CPU, indefinitely. I can open the file in Vim (where it only lets me see the first part of the line) and in Gedit. The file came from debugging Neomutt's use of curses. Thanks. In GNU Emacs 26.3 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.10) of 2019-08-29 built on juergen Recent messages: Loading /home/frederik/.emacs.d/my-mark.el (source)...done Loading /home/frederik/.emacs.d/elpa/ess-20170109.628/lisp/ess-site.el (source)...done Loading /usr/share/emacs/26.3/lisp/progmodes/cc-mode.el.gz... uncompressing cc-mode.el.gz...done Loading /usr/share/emacs/26.3/lisp/progmodes/cc-mode.el.gz...done Loading /home/frederik/.emacs.d/my-compile-next-makefile.el (source)...done For information about GNU Emacs and the GNU system, type C-h C-a. When done with a buffer, type C-x # next-line: End of buffer [2 times] Making completion list... Configured using: 'configure --prefix=/usr --sysconfdir=/etc --libexecdir=/usr/lib --localstatedir=/var --with-x-toolkit=gtk3 --with-xft --with-modules 'CFLAGS=-march=x86-64 -mtune=generic -O2 -pipe -fno-plt' CPPFLAGS=-D_FORTIFY_SOURCE=2 LDFLAGS=-Wl,-O1,--sort-common,--as-needed,-z,relro,-z,now' Configured features: XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND GPM DBUS GSETTINGS GLIB NOTIFY ACL GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB TOOLKIT_SCROLL_BARS GTK3 X11 XDBE XIM MODULES THREADS LIBSYSTEMD LCMS2 Important settings: value of $LC_TIME: en_GB value of $LANG: value of $XMODIFIERS: locale-coding-system: utf-8-unix Major mode: Fundamental Minor modes in effect: global-auto-revert-mode: t shell-dirtrack-mode: t savehist-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 auto-composition-mode: t auto-encryption-mode: t auto-compression-mode: t column-number-mode: t line-number-mode: t Load-path shadows: /home/frederik/.emacs.d/elpa/ess-20170109.628/lisp/ess-rd hides /usr/share/emacs/site-lisp/ess/ess-rd /home/frederik/.emacs.d/elpa/ess-20170109.628/lisp/ess-rutils hides /usr/share/emacs/site-lisp/ess/ess-rutils /home/frederik/.emacs.d/elpa/ess-20170109.628/lisp/msdos hides /usr/share/emacs/site-lisp/ess/msdos /home/frederik/.emacs.d/elpa/ess-20170109.628/lisp/ess-sp3-d hides /usr/share/emacs/site-lisp/ess/ess-sp3-d /home/frederik/.emacs.d/elpa/ess-20170109.628/lisp/ess-r-gui hides /usr/share/emacs/site-lisp/ess/ess-r-gui /home/frederik/.emacs.d/elpa/ess-20170109.628/lisp/ess-bugs-d hides /usr/share/emacs/site-lisp/ess/ess-bugs-d /home/frederik/.emacs.d/elpa/ess-20170109.628/lisp/ess-trns hides /usr/share/emacs/site-lisp/ess/ess-trns /home/frederik/.emacs.d/elpa/ess-20170109.628/lisp/ess-font-lock hides /usr/share/emacs/site-lisp/ess/ess-font-lock /home/frederik/.emacs.d/elpa/ess-20170109.628/lisp/ess-dde hides 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/usr/share/emacs/site-lisp/ess/ess-bugs-l /home/frederik/.emacs.d/elpa/ess-20170109.628/lisp/ess-roxy hides /usr/share/emacs/site-lisp/ess/ess-roxy /home/frederik/.emacs.d/elpa/ess-20170109.628/lisp/ess-xls-d hides /usr/share/emacs/site-lisp/ess/ess-xls-d /home/frederik/.emacs.d/elpa/ess-20170109.628/lisp/make-regexp hides /usr/share/emacs/site-lisp/ess/make-regexp /home/frederik/.emacs.d/elpa/ess-20170109.628/lisp/ess-sp6w-d hides /usr/share/emacs/site-lisp/ess/ess-sp6w-d /home/frederik/.emacs.d/elpa/ess-20170109.628/lisp/ess-custom hides /usr/share/emacs/site-lisp/ess/ess-custom /home/frederik/.emacs.d/elpa/ess-20170109.628/lisp/ess-s4-d hides /usr/share/emacs/site-lisp/ess/ess-s4-d /home/frederik/.emacs.d/elpa/ess-20170109.628/lisp/ess-sas-a hides /usr/share/emacs/site-lisp/ess/ess-sas-a /home/frederik/.emacs.d/elpa/ess-20170109.628/lisp/ess-noweb-mode hides /usr/share/emacs/site-lisp/ess/ess-noweb-mode /home/frederik/.emacs.d/elpa/ess-20170109.628/lisp/mouseme hides /usr/share/emacs/site-lisp/ess/mouseme /home/frederik/.emacs.d/elpa/julia-mode-20191225.858/julia-mode hides /usr/share/emacs/site-lisp/ess/julia-mode /home/frederik/.emacs.d/elpa/ess-20170109.628/lisp/ess-utils hides /usr/share/emacs/site-lisp/ess/ess-utils /home/frederik/.emacs.d/elpa/ess-20170109.628/lisp/ess hides /usr/share/emacs/site-lisp/ess/ess /home/frederik/.emacs.d/elpa/ess-20170109.628/lisp/ess-sas-d hides /usr/share/emacs/site-lisp/ess/ess-sas-d /home/frederik/.emacs.d/elpa/ess-20170109.628/lisp/ess-site hides /usr/share/emacs/site-lisp/ess/ess-site /home/frederik/.emacs.d/elpa/ess-20170109.628/lisp/ess-sas-l hides /usr/share/emacs/site-lisp/ess/ess-sas-l /home/frederik/.emacs.d/elpa/ess-20170109.628/lisp/essd-els hides /usr/share/emacs/site-lisp/ess/essd-els /home/frederik/.emacs.d/elpa/ess-20170109.628/lisp/ess-eldoc hides /usr/share/emacs/site-lisp/ess/ess-eldoc /home/frederik/.emacs.d/elpa/ess-20170109.628/lisp/ess-r-args hides /usr/share/emacs/site-lisp/ess/ess-r-args 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/home/frederik/.emacs.d/elpa/ess-20170109.628/lisp/ess-omg-d hides /usr/share/emacs/site-lisp/ess/ess-omg-d Features: (shadow sort mail-extr emacsbug message rmc puny dired dired-loaddefs rfc822 mml mml-sec epa 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 term/rxvt term/xterm xterm elec-pair cc-mode derived cc-fonts cc-guess cc-menus cc-cmds cc-styles cc-align cc-engine cc-langs cc-bytecomp jka-compr rx edmacro kmacro autorevert filenotify ido ess-toolbar ess-mouse mouseme thingatpt+ thingatpt browse-url ess-menu ess-swv ess-noweb ess-noweb-font-lock-mode ess-bugs-l essd-els ess-sas-d ess-sas-l ess-sas-a ess-sta-d ess-sta-l cc-vars cc-defs make-regexp ess-sp6-d ess-dde ess-sp3-d ess-julia julia-mode julia-mode-latexsubs ess-r-d ess-r-syntax ess-r-completion ess-roxy essddr noutline outline hideshow ess-help ess-r-package ess-s-l ess ess-inf ess-tracebug tramp tramp-compat tramp-loaddefs trampver ucs-normalize shell pcomplete parse-time format-spec advice ess-mode ess-noweb-mode ess-utils time-date ess-generics ess-custom executable ess-compat ess-site savehist iflipb bind-key compile easy-mmode comint ansi-color ring cl help-fns+ wid-edit help-fns radix-tree help-mode server finder-inf gh-common marshal eieio-compat 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 mule-util tooltip eldoc electric uniquify ediff-hook vc-hooks lisp-float-type mwheel term/x-win x-win term/common-win x-dnd tool-bar dnd fontset image regexp-opt fringe tabulated-list replace newcomment text-mode elisp-mode lisp-mode prog-mode register page menu-bar rfn-eshadow isearch timer select scroll-bar mouse jit-lock font-lock syntax facemenu font-core term/tty-colors 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 composite charscript charprop case-table epa-hook jka-cmpr-hook help simple abbrev obarray 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 threads dbusbind inotify lcms2 dynamic-setting system-font-setting font-render-setting move-toolbar gtk x-toolkit x multi-tty make-network-process emacs) Memory information: ((conses 16 329454 16361) (symbols 48 32943 2) (miscs 40 103 133) (strings 32 71935 3550) (string-bytes 1 1946605) (vectors 16 47930) (vector-slots 8 883205 10966) (floats 8 113 448) (intervals 56 312 0) (buffers 992 16))