I've just added some Windows 7 virtual machines to an existing VMWare vSphere 5.1 cluster. The hosts and vCenter are 5.1 with current updates via Update Manager.
Looking at the vSphere client performance graphs, I see random sustained jumps in the guest CPU utilization. These are new VM's with no software installed. They were trimmed-down and optimized according to this guide. The VMWare guest tools are installed.
Any thoughts on what the issue could be? I suspect a guest tools/version interaction, but a root cause would be helpful.