Thanks for the bug report. Just to confirm that this isn't a configuration issue, can you try starting Emacs as `emacs -Q` and reproducing the issue?

If the problem persists in `emacs -Q`, maybe a trace generated by running M-x profiler-start before changing workspaces and M-x profiler-report after returning to the first workspace would help? You can save the profile with profiler-report-save-profile.

Cheers,
Clément.

On 2016-07-27 19:11, aiken wrote:
> I am using the i3 window manager. When I launch emacs (via dmenu) while
> in a workspace, call it workspace A, and switch to workspace B before
> the emacs window appears, then eventually it loads up in A, but during
> this time, emacs' CPU usage is very high. It remains high until I switch
> back to A, at which point its CPU usage becomes normal. I've also tried
> launching emacs with my init.el disabled (commented out) and get the
> same result.
> 
> 
> 
> In GNU Emacs 24.5.1 (x86_64-pc-linux-gnu, GTK+ Version 3.18.9)
>  of 2016-04-17 on lgw01-04, modified by Debian
> Windowing system distributor `The X.Org Foundation', version 11.0.11803000
> System Description:	Ubuntu 16.04.1 LTS
> 
> Configured using:
>  `configure --build x86_64-linux-gnu --prefix=/usr
>  --sharedstatedir=/var/lib --libexecdir=/usr/lib
>  --localstatedir=/var/lib --infodir=/usr/share/info
>  --mandir=/usr/share/man --with-pop=yes
>  --enable-locallisppath=/etc/emacs24:/etc/emacs:/usr/local/share/emacs/24.5/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/24.5/site-lisp:/usr/share/emacs/site-lisp
>  --build x86_64-linux-gnu --prefix=/usr --sharedstatedir=/var/lib
>  --libexecdir=/usr/lib --localstatedir=/var/lib
>  --infodir=/usr/share/info --mandir=/usr/share/man --with-pop=yes
>  --enable-locallisppath=/etc/emacs24:/etc/emacs:/usr/local/share/emacs/24.5/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/24.5/site-lisp:/usr/share/emacs/site-lisp
>  --with-x=yes --with-x-toolkit=gtk3 --with-toolkit-scroll-bars
>  'CFLAGS=-g -O2 -fstack-protector-strong -Wformat
>  -Werror=format-security -Wall' 'CPPFLAGS=-Wdate-time
>  -D_FORTIFY_SOURCE=2' 'LDFLAGS=-Wl,-Bsymbolic-functions -Wl,-z,relro''
> 
> Important settings:
>   value of $LANG: en_GB.UTF-8
>   locale-coding-system: utf-8-unix
> 
> Major mode: Message
> 
> Minor modes in effect:
>   mml-mode: t
>   global-linum-mode: t
>   linum-mode: t
>   show-paren-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
>   auto-fill-function: message-do-auto-fill
>   transient-mark-mode: t
>   abbrev-mode: t
> 
> Recent messages:
> Sending...
> message-send: No methods specified to send by
> Mark set
> Sending...
> message-send: No methods specified to send by
> Mark set
> Sending...
> message-send: No methods specified to send by
> Mark set
> Mark deactivated
> 
> Load-path shadows:
> /home/aiken/.emacs.d/elpa/helm-20160715.2117/helm-multi-match hides
> /home/aiken/.emacs.d/elpa/helm-core-20160716.3/helm-multi-match
> /usr/share/emacs/24.5/site-lisp/debian-startup hides
> /usr/share/emacs/site-lisp/debian-startup
> 
> Features:
> (pp shadow sort gnus-util mail-extr emacsbug message format-spec rfc822
> mml mml-sec 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 help-mode ido tango-theme linum edmacro
> kmacro cl-loaddefs cl-lib paren cus-start cus-load easymenu package
> epg-config time-date tooltip electric uniquify ediff-hook vc-hooks
> lisp-float-type mwheel x-win x-dnd tool-bar dnd fontset image regexp-opt
> fringe tabulated-list newcomment lisp-mode prog-mode register page
> menu-bar rfn-eshadow timer select scroll-bar mouse jit-lock font-lock
> syntax facemenu font-core frame cham georgian utf-8-lang misc-lang
> vietnamese tibetan thai tai-viet lao korean japanese hebrew greek
> romanian slovak czech european ethiopic indian cyrillic chinese
> case-table epa-hook jka-cmpr-hook help simple abbrev minibuffer 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 make-network-process dbusbind
> gfilenotify dynamic-setting system-font-setting font-render-setting
> move-toolbar gtk x-toolkit x multi-tty emacs)
> 
> Memory information:
> ((conses 16 148256 14891)
>  (symbols 48 23209 0)
>  (miscs 40 214 233)
>  (strings 32 30777 8686)
>  (string-bytes 1 780663)
>  (vectors 16 14596)
>  (vector-slots 8 441793 11029)
>  (floats 8 87 340)
>  (intervals 56 789 779)
>  (buffers 960 14)
>  (heap 1024 45744 1545))
> 
> 
> 
>