PC-BSD 10.0 vs. PC-BSD 9.2 vs. Ubuntu 13.10 Benchmarks
Ubuntu 13.10 with its GCC 4.8 compiler was generally ahead of PC-BSD 10.0 with LLVM/Clang. Some tests may come in a later article on Phoronix comparing the GCC performance between operating systems while this test was intended to just test the "out of the box" experience with using the defaults chosen by the distribution vendor.
Where LLVM Clang continues to do smashingly better than GCC is at much faster compile times.