For many of the computational benchmarks, the compiler doesn't yield a heck of a lot of difference in the performance of the resulting binaries.
N-Queens is another OpenMP test case.
Overall, there aren't too many test cases conducted where GCC 4.8.0 yielded significant performance differences over GCC 4.7.2. With Clang, however, it seems LLVM/Clang 3.3 is yielding significantly faster binaries over LLVM/Clang 3.2 for a number of the open-source Linux benchmarks. Now to hope that OpenMP support will be committed soon for LLVM/Clang...
LLVM/Clang 3.3 will be officially released in June at which time there will be plenty more x86 and ARM compiler benchmarks.