Firefox, GIMP unusuable slow by root running kubuntu

Binary package hint: kubuntu-desktop

Problem:
Logged in as root both, GIMP and Firefox were unusuable slow when a top-level menu entry (Files...) was activated (mouse-click) though browsing was fluently possible.
It took about 5 seconds or more until the pull-down menu content appeared and the same time to select one of those entries (like "Open file", "Print", etc.)
The reason was that libcanberra was loaded on every trigger of a menu entry, with every click on a menu button, looked up several symbols and then was finalized (unloaded)
Starting firefox from console with "export LD_DEBUG=files", "firefox" showed the time consuming action:

---quote start---
     opening file=/usr/lib/libcanberra-0.22/libcanberra-pulse.so [0]; direct_opencount=1
     /usr/lib/libcanberra-0.22/libcanberra-pulse.so: error: symbol lookup error: undefined symbol: libcanberra_pulse_LTX_pulse_driver_open (fatal)
     ...
     /usr/lib/libcanberra-0.22/libcanberra-pulse.so: error: symbol lookup error: undefined symbol: libcanberra_pulse_LTX_driver_playing (fatal)
     calling fini: grep [0]
     ...
     calling fini: /usr/lib/libcanberra-0.22/libcanberra-pulse.so [0]
     file=/usr/lib/libcanberra-0.22/libcanberra-pulse.so [0]; destroying link map
---quote end---

Different from that is how the same activity was handled as regular user:

---quote start---
     calling init: /usr/lib/libcanberra-0.22/libcanberra-pulse.so
     /usr/lib/libcanberra-0.22/libcanberra-pulse.so: error: symbol lookup error: undefined symbol: libcanberra_pulse_LTX_pulse_driver_open (fatal)
      ...
     /usr/lib/libcanberra-0.22/libcanberra-pulse.so: error: symbol lookup error: undefined symbol: libcanberra_pulse_LTX_driver_playing (fatal)
---quote end---

No unloading/finalisation of the library/symbols. For that non-root user the libcanberra was loaded just once much earlier in the start-up phase of firefox and was not finalized in conjunction with a menu-button-click:

---quote start---
     calling init: /usr/lib/libcanberra.so.0
     calling init: /usr/lib/libcanberra-gtk.so.0
     calling init: /usr/lib/gtk-2.0/modules/libcanberra-gtk-module.so
---quote end---

As the complete console debug-output shows, the strategy of firefox as root is to load libraries and symbols lazy on request while firefox run as non-root preloaded the libraries.

Workaround:
Purge the libcanberra-gtk-module package to let GIMP run as root smoothly, and additionally to purge the canberra-pulse package to let firefox become usable again.

Environment:
Installed ubuntu 10.04,
switched to kubuntu having root- and one user account installed,
created a new user account under kubuntu.
Audio is default pulseaudio.

The behaviour was independent of different deskstop styles, GTK-widget sets or other tunings in the system-settings and GIMP was unused so far as root and as non-root.
Also tried a different Firefox Theme.
There are no defect or packages or unresolved dependencies.
Setting the environment variable "GTK_MODULES" (was preset to "libcanberra-gtk-module") to the empty string or unsetting it at all had no effect.
The system is freshly installed, this workaround was my last action in fine-tuning (so far).

Reflection:
The libcanberra-gtk-module is described as an automatic hook for applications using GTK and it seems it was the origin trigger which finally caused the repeated load/unload.
But Firefox was still was still misfunctioning without that module while GIMP was smooth to handle again.
Both packages are marked as ubuntu supported, they caused no conflicts when installed - and all other programs if have run so far were not affected when run as root.
There was never a sound in conjuction with menu actions though system sounds and audio play are working.

Lasting problems/questions:
Firefox run as root acted different in loading libraries as root and non-user.
GIMP, definitely in delivery state, acted different too.
If there should be a possibility, which i am not aware of, to configure root vs. non-root behaviour of Firefox and GIMP this way it could be better, more obviously, documented.
Since both applications were affected, it seems the reason is neither firefox nor GIMP.