PC-BSD 10.0 vs. PC-BSD 9.2 vs. Ubuntu 13.10 Benchmarks
Ubuntu 13.10 generally did the best in the computational tests with it using the GCC 4.8 compiler by default while PC-BSD 10.0 is using LLVM Clang 3.3 in place of using an old GPLv2-licensed GCC 4.2 compiler.
More recent versions of GCC are available from FreeBSD ports, but they are not shipped by default.