Comment 6 for bug 1276186

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