Really bizarre issue here; I suspect it's X-related. This may be better suited to the Linux/Unix SE, but I figured there might be more domain-specific expertise here.

Often (but not 100% of the time), if I run Emacs and Chromium (or google-chrome, I'm on Ubuntu) at the same time, then UI updates on Emacs take ages to show. As in, I'll try to scroll around the package menu and it will take 45 seconds to render a few dozen lines worth of scrolling. It seems to go both ways: I'm updating 31 packages in the background as I type this and there's a few seconds of lag between every character I type and the on-screen rendering.

This issue occurs with both emacsclients and stand-alone Emacs sessions. I have 6 cores and I see that only one of them is being used at the moment, which I think must be the cause of the issue. I 'm only at 60% memory usage with almost no swap space being used, so it's not a question of the system being over-taxed.

It looks like the lag spikes correlate with CPU-intensive actions in Emacs. It's almost as if chromium and Emacs have decided to run on the same core and compete for cycles, but I can't imagine why.

I'm on the latest Ubuntu release, via Xubuntu, and I use XMonad as my window manager. I've never had any other pair of programs have this kind of issue. Firefox doesn't cause this problem, I only discovered it recently after switching to Chrome. What's going on here?

  • Can you reproduce it when you run Emacs without your init file? (emacs -Q) What about if you start up Chrome with a different profile instead?
    – db48x
    Dec 9, 2015 at 5:38
  • @db48x: Yes, the behavior is the same in both of those circumstances (emacs -Q and chromium-browser --temp-profile). Closing one or the other fixes the problem. Dec 9, 2015 at 6:40
  • Also, perhaps unsurprisingly, the problem isn't present if I run it via emacs -nw. Dec 9, 2015 at 6:42
  • That is curious. I guess you could try profiling one or the other to find out what's going on.
    – db48x
    Dec 9, 2015 at 12:58
  • Same problem here, but just noticed that the spotify-client also causes this.
    – tristan
    Feb 3, 2016 at 0:06

3 Answers 3


Try running "xcompmgr -n &". (See https://michaelheap.com/google-chrome-stealing-focus-repainting-in-xmonad/)

This finally fixed emacs for me, but, ironically, it has slowed google-chrome down in the current session I am in.


This isn't exactly an answer, but it kind of is. I just don't have rep to comment other wise I would.

This happens to me as well, except I do not use xmonad, I use i3wm, but it goes away if I have the chromium window tiled with another window on the same screen. I also experience this with steam/steam games.

Running htop reveals no process utilizing large amounts of CPU. I speculate that the problem is in an thread that typically "waits" synchronously rather than asynchronously somewhere in Emacs.


use firefox instead. chrome is buggy. besides, keysnail is a great firefox ONLY addon to convert firefox to emacs

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