KVM offered the fastest performance in all of the tests except for SQLite, where VirtualBox was the fastest but that is due to a bug.
Not true - Xen won one of the benchmarks as well: NAS Parrallel Benchmarks v3.3 - Test/Class: IS.C
Bare Metal: 141.82
Virtual Box: 78.24
But as others have said, it would be interesting to see the results of Xen without the HVM as well...