Description of problem:
Volume up and down are associated to "Audio raise volume" and "Audio lower volume" keys respectively on the keyboard shortcuts screen. When either is pressed the translucent panel with the speaker sign is shown on the primary monitor, but the operation uses a lot of CPU -- all system slows down momentarily, and top shows a spike on CPU usage by "Xorg" process.

Version-Release number of selected component (if applicable):
gnome-shell-3.2.1-2.fc16.x86_64

How reproducible:
Always.

Steps to Reproduce:
1. press keyboard shortcuts for raising or lowering volume
2.
3.
  
Actual results:
Audio volume panel shows up on primary monitor and system slows down noticeably for a couple of seconds.

Expected results:
No impact on performance (worked just fine on F15).

Additional info:
Using proprietary nvidia driver 285.05.09. Changing volume level by using the mouse wheel on the speaker icon on the gnome-shell top bar works fine.