Run 'emacs -Q bar.c' (this file is attached) Goto a line inside the initializer e.g. 'M-x goto-line RET 9522' emacs will hang for ~50 seconds on a 100% cpu on a Intel i7 @ 3.40GHz. This bug seems to be introduced by commit d3090a3a3e22c4b0f4e0e833942f5942eb392c51 (HEAD, refs/bisect/bad) Author: Alan Mackenzie Date:   Fri Feb 2 20:46:35 2018 +0000     CC Mode: Fix an enum intro being parsed as defun-block-intro          * lisp/progmodes/cc-engine.el (c-inside-bracelist-p): Return a bufpos rather     than t for the enum case.     (c-add-stmt-syntax, c-guess-continued-construct): Replace     c-looking-at-or-maybe-in-bracelist by c-inside-bracelist-p, since the former     does not recognize enum brace lists, but the latter does.          * lisp/progmodes/cc-fonts.el (c-get-fontification-context): Replace     c-looking-at-or-maybe-in-bracelist by c-inside-bracelist-p. I generated a profile and 95% of time is spent in c-inside-bracelist-p called from c-get-fontification-context. In GNU Emacs 27.0.50 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.22.25)  of 2018-03-17 built on lgw01-amd64-055 Windowing system distributor 'The X.Org Foundation', version 11.0.11803000 System Description: Ubuntu 17.10 Recent messages: For information about GNU Emacs and the GNU system, type C-h C-a. Configured using:  'configure --build=x86_64-linux-gnu --prefix=/usr  '--includedir=${prefix}/include' '--mandir=${prefix}/share/man'  '--infodir=${prefix}/share/info' --sysconfdir=/etc --localstatedir=/var  --disable-silent-rules '--libdir=${prefix}/lib/x86_64-linux-gnu'  '--libexecdir=${prefix}/lib/x86_64-linux-gnu' --disable-maintainer-mode  --disable-dependency-tracking --prefix=/usr --sharedstatedir=/var/lib  --program-suffix=-snapshot --with-modules=yes --with-x=yes  --with-x-toolkit=gtk3 --with-xwidgets=yes 'CFLAGS=-g -O2  -fdebug-prefix-map=/build/emacs-snapshot-lB2ym1/emacs-snapshot-94474=. -fstack-protector-strong  -Wformat -Werror=format-security' 'CPPFLAGS=-Wdate-time  -D_FORTIFY_SOURCE=2' 'LDFLAGS=-Wl,-Bsymbolic-functions -Wl,-z,relro'' Configured features: XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND GPM DBUS GSETTINGS NOTIFY LIBSELINUX GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB TOOLKIT_SCROLL_BARS GTK3 X11 MODULES THREADS XWIDGETS LIBSYSTEMD LCMS2 Important settings:   value of $LANG: en_GB.UTF-8   locale-coding-system: utf-8-unix Major mode: C/*l Minor modes in effect:   diff-auto-refine-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   transient-mark-mode: t   abbrev-mode: t Load-path shadows: /usr/share/emacs/site-lisp/llvm-4.0/tablegen-mode hides /usr/share/emacs/site-lisp/llvm-5.0/tablegen-mode /usr/share/emacs/site-lisp/llvm-4.0/emacs hides /usr/share/emacs/site-lisp/llvm-5.0/emacs /usr/share/emacs/site-lisp/llvm-4.0/llvm-mode hides /usr/share/emacs/site-lisp/llvm-5.0/llvm-mode /usr/share/emacs/site-lisp/rst hides /usr/share/emacs/27.0.50/lisp/textmodes/rst /usr/share/emacs/site-lisp/dictionaries-common/flyspell hides /usr/share/emacs/27.0.50/lisp/textmodes/flyspell /usr/share/emacs/site-lisp/dictionaries-common/ispell hides /usr/share/emacs/27.0.50/lisp/textmodes/ispell Features: (shadow sort mail-extr emacsbug message rmc puny dired dired-loaddefs format-spec rfc822 mml mml-sec password-cache epa derived epg epg-config 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 vc-git diff-mode easy-mmode map seq byte-opt gv bytecomp byte-compile cconv cc-mode cc-fonts easymenu cc-guess cc-menus cc-cmds cc-styles cc-align cc-engine cc-vars cc-defs cl-loaddefs cl-lib elec-pair time-date 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 dbusbind inotify lcms2 dynamic-setting system-font-setting font-render-setting xwidget-internal move-toolbar gtk x-toolkit x multi-tty make-network-process emacs) Memory information: ((conses 16 119309 10422)  (symbols 48 22894 1)  (miscs 40 83 136)  (strings 32 35675 2207)  (string-bytes 1 1073774)  (vectors 16 18053)  (vector-slots 8 536564 11124)  (floats 8 57 70)  (intervals 56 417 1)  (buffers 992 13))