Benchmark testing performed by Phoronix indicate that PCLOS 2010 is the runaway winner.
This comparison of Ubuntu 10.04, Mandriva 2010.1, PCLinuxOS 2010, and openSUSE 11.3 produced some of the most interesting results in terms of comparing different Linux desktop distributions.
Looking at the number of wins for the 12 tests, PCLinuxOS 2010 Beta ended up winning in six of the tests while Mandriva, Ubuntu, and openSUSE each took two. In some tests it was fierce competition between the radically different distributions.
Intriguing results were the OpenGL tests where Mandriva and the Mandriva-based PCLinuxOS are sharply outperforming Ubuntu and openSUSE at least with a Mobility Radeon X1400 and its open-source R500 driver stack.
In other tests, Mandriva had struggled a great deal while PCLinuxOS leveraging the BFS scheduler and other optimizations appears to be of measurable benefit.