Attached is simple makefile with a bunch of echo statements that reproduce  
the output of an actual compilation. I had to gzip and attach it, in order  
to avoid the large lines getting messed up by E-mail formatting.

Saving this makefile, and hitting F5, or executing "compile" makes emacs  
spin with 100% CPU utilization for about five seconds, before it starts  
responding again. Then, going to the compilation output buffer, and M-> to  
go the end of the buffer, that also pegs emacs for another 4-5 seconds, at  
100% cpu.

Yup, these are very long lines. But that's the end result from automake and  
libtool. This is the real world, when it comes to C++ development these  
days...




In GNU Emacs 25.3.1 (x86_64-redhat-linux-gnu, GTK+ Version 3.22.19)
 of 2017-09-14 built on buildvm-31.phx2.fedoraproject.org
Windowing system distributor 'Fedora Project', version 11.0.11905000
Configured using:
 'configure --build=x86_64-redhat-linux-gnu
 --host=x86_64-redhat-linux-gnu --program-prefix=
 --disable-dependency-tracking --prefix=/usr --exec-prefix=/usr
 --bindir=/usr/bin --sbindir=/usr/sbin --sysconfdir=/etc
 --datadir=/usr/share --includedir=/usr/include --libdir=/usr/lib64
 --libexecdir=/usr/libexec --localstatedir=/var
 --sharedstatedir=/var/lib --mandir=/usr/share/man
 --infodir=/usr/share/info --with-dbus --with-gif --with-jpeg --with-png
 --with-rsvg --with-tiff --with-xft --with-xpm --with-x-toolkit=gtk3
 --with-gpm=no --with-xwidgets --with-modules
 build_alias=x86_64-redhat-linux-gnu host_alias=x86_64-redhat-linux-gnu
 'CFLAGS=-DMAIL_USE_LOCKF -O2 -g -pipe -Wall -Werror=format-security
 -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong
 --param=ssp-buffer-size=4 -grecord-gcc-switches
 -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -m64 -mtune=generic'
 LDFLAGS=-Wl,-z,relro
 PKG_CONFIG_PATH=:/usr/lib64/pkgconfig:/usr/share/pkgconfig'

Configured features:
XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND DBUS GCONF GSETTINGS NOTIFY
ACL LIBSELINUX GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB
TOOLKIT_SCROLL_BARS GTK3 X11 MODULES XWIDGETS

Important settings:
  value of $LANG: en_US.utf8
  value of $XMODIFIERS: @im=ibus
  locale-coding-system: utf-8-unix

Major mode: Compilation

Minor modes in effect:
  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
  buffer-read-only: t
  line-number-mode: t
  transient-mark-mode: t

Recent messages:
Loading /usr/share/emacs/site-lisp/site-start.d/anthy-init.el (source)...done
Loading /usr/share/emacs/site-lisp/site-start.d/autoconf-init.el (source)...done
Loading /usr/share/emacs/site-lisp/site-start.d/desktop-entry-mode-init.el (source)...done
Loading /usr/share/emacs/site-lisp/site-start.d/git-init.el (source)...done
Loading /usr/share/emacs/site-lisp/site-start.d/mercurial-site-start.el (source)...done
Loading /usr/share/emacs/site-lisp/site-start.d/rpm-spec-mode-init.el (source)...done
For information about GNU Emacs and the GNU system, type C-h C-a.
Compilation finished
Mark set
next-line: End of buffer

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message idna dired format-spec rfc822
mml mml-sec password-cache epg epg-config gnus-util mm-decode mm-bodies
mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader sendmail
rfc2047 rfc2045 ietf-drums mm-util help-fns help-mode easymenu
cl-loaddefs pcase cl-lib mail-prsvr mail-utils compile comint ansi-color
ring time-date mule-util tooltip eldoc electric uniquify ediff-hook
vc-hooks lisp-float-type mwheel x-win term/common-win x-dnd 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 dbusbind inotify
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 93448 8431)
 (symbols 48 20589 0)
 (miscs 40 53 146)
 (strings 32 16324 4384)
 (string-bytes 1 479802)
 (vectors 16 12525)
 (vector-slots 8 441765 5250)
 (floats 8 175 46)
 (intervals 56 298 0)
 (buffers 976 19))