A benchmark with gcc-llvm vs gcc (4.1.2, a 2007 version). http://www.phoronix.com/scan.php?page=article&item=apple_llvm_gcc&num=1 To resume, Gcc is from a little slower to 30% faster. A benchmark to compare Gcc to Clang is annonced. I hope they will test also Gcc 4.4.