hud-service is consistently taking > 10% of CPU time, which is more than compiz. This is a high proportion of a reasonably beefy machine (i7 quad-core 1.87-3.2 GHz). I have used the HUD in this session, but it this CPU time is being spent even when the HUD is not actually in use.
top - 13:46:19 up 4:44, 3 users, load average: 0.10, 0.20, 0.24
Tasks: 347 total, 2 running, 291 sleeping, 0 stopped, 54 zombie
Cpu(s): 8.6%us, 1.7%sy, 0.0%ni, 89.6%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Mem: 8111384k total, 6869168k used, 1242216k free, 313336k buffers
Swap: 7778300k total, 112k used, 7778188k free, 3653024k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
26735 abentley 20 0 527m 27m 17m S 18 0.4 0:09.17 gnome-system-mo
2625 abentley 20 0 688m 13m 3468 S 14 0.2 39:59.48 hud-service
3083 abentley 20 0 1425m 330m 41m S 13 4.2 8:51.99 thunderbird-bin
2437 abentley 20 0 1577m 277m 49m S 12 3.5 25:44.78 compiz
1451 root 20 0 203m 86m 22m S 9 1.1 10:51.42 Xorg
2623 abentley 20 0 618m 45m 11m S 3 0.6 9:03.28 unity-panel-ser
3175 abentley 20 0 627m 25m 4492 S 2 0.3 4:48.09 beam.smp
3273 abentley 20 0 1446m 440m 54m S 2 5.6 10:57.06 firefox
2459 abentley 20 0 541m 12m 8312 S 1 0.2 3:01.98 indicator-multi
2407 abentley 20 0 30400 5892 628 S 1 0.1 2:37.91 dbus-daemon
2662 abentley 20 0 413m 6528 4064 S 1 0.1 2:32.36 indicator-appli
5509 abentley 20 0 580m 23m 11m S 1 0.3 0:19.43 gnome-terminal
2451 abentley 9 -11 571m 7548 4704 S 1 0.1 4:45.45 pulseaudio
2722 root 20 0 0 0 0 S 1 0.0 0:28.48 flush-ecryptfs-
3404 abentley 20 0 450m 51m 24m S 1 0.7 0:03.61 plugin-containe
15646 root 20 0 0 0 0 R 1 0.0 0:03.58 kworker/1:2
26788 postgres 20 0 128m 8168 5316 S 1 0.1 0:00.06 postgres
ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: unity 5.6.0-0ubuntu4
ProcVersionSignature: Ubuntu 3.2.0-18.29-generic 3.2.9
Uname: Linux 3.2.0-18-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 1.94.1-0ubuntu2
Architecture: amd64
CompizPlugins: [core,bailer,detection,composite,opengl,compiztoolbox,decor,commands,move,snap,gnomecompat,resize,grid,regex,place,vpswitch,mousepoll,animation,imgpng,expo,session,ezoom,unitymtgrabhandles,resizeinfo,wall,workarounds,fade,scale,unityshell]
Date: Wed Mar 21 13:44:11 2012
EcryptfsInUse: Yes
InstallationMedia: Ubuntu 10.10 "Maverick Meerkat" - Release amd64 (20101007)
ProcEnviron:
TERM=xterm
PATH=(custom, user)
LANG=en_CA.UTF-8
SHELL=/bin/bash
SourcePackage: unity
UpgradeStatus: Upgraded to precise on 2012-03-02 (18 days ago)
seems like bug #938584