Cpu Unit and virtual processor

Hello,

I have some questions about cpu for kvm...
The beginning of this is that I have a Windows server which had frozen many times...
It had 2 sockets and 4 cores so I upgraded it to 4 sockets and 4 cores. It was better because the CPU utilization of the VM evolved from 100% to 70% at the max value.
But I had some times other freeze.... And I found this option : CPU Unit and I configure it from 1000 to 20000. Now I don't have any freeze.

So, when I set some socket or core to the VM, which is the link between this virtual processor and the processor of the hypervisor proxmox?
And other question, what is the link between CpuUnit and the value of the virtual processor?

I checked this link : http://forum.proxmox.com/threads/889...=4643#post4643
But it doesn't explain some link between virtual processor and cpu unit.

Thank you for your explanations!