System becomes unresponsive, ibus-ui-daemon takes ~150 % cpu

Status changed to 'Confirmed' because the bug affects multiple users.

As for my enviroment, I notice it very often hangs after cromium-browser close.

UPD: mine locale is ru_RU

I am also affected on ubuntu 14.04. It often happens when minimizing or closing a window.

Based on http://askubuntu.com/a/490326/7146 I determined that I don't need ibus-daemon, since I don't use multilingual input. I disabled it by switching System Setting > Language to none rather than ibus, and then restarting. Since then I have not suffered from slowdowns in the middle of application use. (Of course, this is not a suitable workaround for anyone who needs multilingual input.)

However, I still encounter a slowdown/hang on minimising/closing windows, as reported here https://bugs.launchpad.net/ubuntu/+source/xorg/+bug/1314587

On a clean installation of 14.04 I have this problem, especially right when I close a terminal window. Restarting lightdm allows me to log back in and bring CPU usage to normal, but of course I will lose all unsaved work when retsarting lightdm.

Happens for me on 14.04 when i click on "minimize button"

I found out that it is caused by gnome settings in your home directory. So reinstalling ubuntu won't help to fix it.
below command have solved the issue for me:
gsettings set org.gnome.desktop.background show-desktop-icons true

I see this problem when I run Geary 0.8 on Ubuntu 14.10. I've had to disable IBus as a workaround.

I also experienced this issue when using the composer in Geary 0.8.1 under 14.10 x64. Disabling IBus worked for me.

If someone ever gets assigned to this bug, feel free to contact me for help testing.

I'm still seeing this behavior in Ubuntu 15.04 when typing in Geary 0.9.0.

With Lubuntu 14.04 64bits (Toshiba Satellite) and Ubuntu 14.04 64bits (Dell Latitude 7440) ibus freeze the LXDE desktop or turn very high CPU usage with Chromium, GnuCash and Geany. When I disabled the ibus the system is ok but is not possible to type the accents on spanish keyboard á é í ó ú.

Bug 1271839 may be related. I saw both the high CPU usage and extreme RAM usage (about 1 megabyte/second leak).
It happened when I minimized Chrome, but continued long after I killed all the chrome processes.
ibus-ui-gtk3 got up to 2+ gigabytes of ram pretty quickly.

Putting more details at bug 1271839.

I don't run Chromium, and it still happens on a clean Lubuntu 15.04 install

Affects me when simply writing text in gedit!

Killing ibus-daemon in the terminal cuts the CPU usage and restores responsiveness.

Affects me too on Ubuntu 15.04.

ibus-daemon eats up cpu when i use ibus-pinyin to add receiver email with thunderbird and have address autocomplete enabled.

I can confirm that disabling Desktop Icons caused this issue, and re-enabling it solved it instantly.

Ubuntu 14.04 - Updated as of 12/01/2016

Ubuntu 14.04 - Confirmed as well. Everything lags, and non responsive. Disabling ibus get rids of the problem.

So, has anyone found out if this is an ibus bug or Gnome bug? How could we proceed?

I had the same issue on ubuntu 16.04. When I used F2 to rename files, nautilus crashed when I did it to the third file. After that I didn't give up. Still the nautilus crashed when I left-clicked the nautilus.

I too experience this problem, can't rename files/dirs in nautilus, when typing a letter it behaves like an enter. Like mentioned here: https://bugs.launchpad.net/ubuntu/+source/ibus/+bug/1385292

On 16.04 with Dell XPS13-9350, disabling ibus did not resolve it for me. I have a Dell T3240 and there it just runs fine. I'm guessing it has to do something with the input, like touchscreen/touchpad?