openSUSE Tumbleweed vs. Manjaro vs. Debian 8.0 vs. Fedora 21 vs. Ubuntu 14.10
The Flexible I/O Tester (FIO) disk test results were rather close between distributions, but openSUSE Tumbleweed with its usage of XFS on the home directory (where Phoronix Test Suite tests are installed by default) and Btrfs on the root file-system seemed to have some performance wins for some of the disk tests.
With PostMark the results were very close except for Debian 8.0 Testing taking a slight lead while Manjaro Linux 0.8.12 fell behind.