Performance issues on new HW

As part of a project, old server hardware was replaced with shiny new hardware. Beside the server hardware, storage hardware and infrastructure was also replaced. The new hardware was installed beside the old hardware and because the customer has a high virtualization ratio, nearly all servers were VMs and the migration of the VMs was was done without downtime. The customer uses a Windows 2008 R2 failover cluster for file services and MS SQL Server.