With the VX machines, the clients often confuse the hardware itself with the services and resources. VMs are configured according to resources - memory, hard disk capacity, and network. These resources, including memory and processor, are actually shared on the VX Series.
So, if the server's processor is underpowered or unreliable for the VMs, many of the VMs will encounter issues. Ideally, the physical server configuration should align more closely with the needs of the virtual servers.