Windows 7 Guest + Audio Enabled = High CPU when idle

[brandonkirsch]

I noticed recently that my VirtualBox process was consuming 40-50% on my host OS while my Windows 7 guest was idling happily away. `top` gave me the impression that VirtualBox was eating up every idle cycle on one of my two cores.

I did some digging, found the Windows 7 `perfmon` tool and checked my interrupts per second. They were steady at 1000+ which can lead to undesirable behavior in a virtualized environment.

The guest was reporting very low usage (1-5%, mostly taken by taskman itself to do the polling and reporting) so I figured it had to be a guest driver issue. I disabled my Intel ACH soundcard using Windows Device Manager in the guest and rebooted. Lucky guess to go after the sound driver first: Now my VirtualBox process only eats about 10% while idle as reported by `top` on my host. My interrupts per second as reported by the guest are almost 0 now, but they do spike a little bit as I move my mouse around as expected.

Anyways, I got my problem solved (at the expense of no sound in the guest, oh well who needs it for SQL Studio?) and thought I would share it with others. I'm using PUEL 3.2.16 on OpenSUSE 11.4, so I can't say for sure that this issue still exists in the VirtualBox 4 series.. but if you have high cpu load on the host with low cpu load on the Windows guest, you can try disabling sound within the guest and see if it works for you.