Ubuntu 12.04 KVM/Xen Virtualization: Intel vs. AMD
John The Ripper's Blowfish performance with KVM was close to bare metal and running at the same relative speed with Ubuntu 12.04 on the Intel and AMD processors.
MAFFT in a virtualized environment was running much slower, but was within a few percentage points between the latest-generation Intel and AMD processors.
Building out the Linux 3.1 kernel under KVM happened at 86% the speed of bare metal on the Intel Core i7 3960X configuration while with the AMD FX-8150 it happened at 93% the speed.
C-Ray on the Core i7 3960X was at 95% the native speed for Xen and KVM virtualization methods from the Precise Pangolin while with the FX-8150 with KVM it was at 99% the speed.