Host: Ubuntu Gutsy i386
Guest: Windows XP Professional SP2
After installing iTunes 7.5 from Apple's website I have noticed that VirtualBox uses 100% of the CPU. This is a dual core system (Core Duo T2500 @ 2.0 GHz) so actually only one core at once is at 100%, but I suppose that it would use almost 100% on a single core machine. This obviously makes the machine heat up too. Since I'm new to VirtualBox and I've used it for less than a week, I was unsure about if the VM always used the 100% of the CPU or not, so I first tried to disable tickless (nohz=off) on the host and ACPI on the guest too but that didn't help. Then I noticed that if I logged off the session in the guest CPU usage dropped, so I deduced it should be a Windows process or service what was causing the problem and found it to be iTunesHelper, however in the Windows Task Manager CPU usage for iTunesHelper was around 0-2% as expected so I understand it is a virtual machine issue. After disabling iTunesHelper in the registry so it doesn't load at logon CPU usage was normal again. Then I switched back to ACPI and re-enabled tickless and everything is fine now with iTunesHelper disabled.
