Swift versus C gcc fastest programs Always look at the source code. These are only the fastest programs. Do some of them use manually vectorized SIMD? Look at the other programs. They may seem more-like a fair comparison to you. mandelbrot source secs mem gz busy cpu load Swift 1.35 42,752 1141 5.36 99% 99% 99% 100% C gcc 1.27 31,792 1135 5.08 100% 100% 99% 100% fannkuch-redux source secs mem gz busy cpu load Swift 8.24 7,824 1097 32.69 98% 99% 100% 100% C gcc 7.58 872 910 29.61 100% 98% 99% 93% pidigits source secs mem gz busy cpu load Swift 0.89 9,256 600 0.91 3% 0% 0% 99% C gcc 0.59 2,444 1090 2.37 100% 100% 100% 98% fasta source secs mem gz busy cpu load Swift 1.41 26,396 2090 4.73 80% 80% 96% 79% C gcc 0.78 1,156 1463 0.78 0% 0% 0% 100% reverse-complement source secs mem gz busy cpu load Swift 1.81 781,992 1286 2.28 3% 0% 48% 75% C gcc 0.86 712,208 820 1.27 99% 28% 1% 19% n-body source secs mem gz busy cpu load Swift 5.32 10,456 1365 5.37 100% 0% 0% 0% C gcc 2.18 768 1633 2.19 0% 100% 0% 0% spectral-norm source secs mem gz busy cpu load Swift 1.43 8,144 601 5.68 100% 99% 99% 99% C gcc 0.40 872 1197 1.58 100% 100% 100% 98% k-nucleotide source secs mem gz busy cpu load Swift 13.56 256,964 1367 52.30 96% 95% 96% 99% C gcc 3.72 130,260 1506 12.07 100% 89% 78% 57% binary-trees source secs mem gz busy cpu load Swift 16.15 699,872 862 51.81 77% 66% 79% 100% C gcc 1.54 168,832 809 4.35 60% 67% 57% 100% regex-redux source secs mem gz busy cpu load Swift 23.14 1,059,096 745 48.76 92% 37% 46% 36% C gcc 0.80 152,172 1397 2.01 52% 99% 48% 53% Swift Swift version 5.5-dev (LLVM f9e846e117057c8, Swift a58e8c181f2e258) Target: x86_64-unknown-linux-gnu C gcc gcc (Ubuntu 10.3.0-1ubuntu1) 10.3.0 all Swift programs & measurements all C gcc programs & measurements