Ubuntu 14.04 On Amazon EC2: Xen PV vs. HVM
The HPC Challenge results between the PV and HVM c3.large instances were close to the same except for the HVM instance performing faster for the G-Ffte workload (computing Discrete Fourier Transforms) while the EP-STREAM Triad (memory bandwidth test) was faster on the para-virtualized instance. HVM also had a lower random ring latency for HPCC and greater max ping pong bandwidth.
For many conventional applications, the Xen 4.2 PV vs. HVM performance was very close for the Amazon EC2 c3.large benchmarking.