FWIW .. I think the phoronix benchmarks got similar results. http://www.phoronix.com/scan.php?page=article&item=gcc_llvm_clang&num=1 http://www.phoronix.com/scan.php?page=article&item=llvm_gcc_atom&num=1 IMHO, 10% is not a huge performance difference though. Pedro.