Hello, Interesting virtualization overhead benchmark comparison between Native/baremetal, Xen4.1 on Ubuntu 11.10, XenServer 6.0, RHEV3 (KVM), Vsphere5, Hyper-V: http://blog.exceliance.fr/2012/04/24/hypervisors-virtual-network-performance-comparison-from-a-virtualized-load-balancer-point-of-view/ Focusing on haproxy loadbalancer workload.. so a lot of network IO. -- Pasi