How can I find out what ibus-daemon and ibus-ui-gtk3 are doing?
Solution 1:
This is the intelligent input bus - is an input method framework for multilingual input. If you don't use any different keyboard layouts for ex. japanese /asian etc.
Try to disable it in System Setting -> Language (something like input method from ibus to none)
Try to killall ibus-daemon and tell us if cpu is still has a high load.