Swift versus Rust fastest performance Always look at the source code. If the fastest programs are hand-written vector instructions, does the host language matter? You might be more interested in the less optimised programs — more seconds, less gz source code. fannkuch-redux source secs mem gz cpu secs Rust #6 3.51 11,036 1253 13.93 Rust #4 7.21 10,932 1020 28.34 Rust #5 7.77 10,932 1016 30.49 Swift #3 8.24 11,220 1097 32.62 Swift 34.60 11,220 451 34.59 Rust #2 17.99 11,036 1191 70.95 n-body source secs mem gz cpu secs Rust #9 2.81 11,068 1874 2.81 Rust #7 3.27 11,068 1753 3.27 Rust #6 3.92 11,068 1790 3.92 Swift #5 5.44 14,780 1365 5.43 Swift #7 5.44 14,792 1326 5.44 Swift #4 5.45 14,780 1355 5.45 Rust #3 5.63 11,068 1540 5.63 Rust 5.63 11,068 1480 5.63 Swift #8 5.92 14,820 1681 5.92 Swift #6 5.93 11,340 1194 5.93 Rust #2 5.98 11,068 1805 5.98 Rust #8 6.01 11,068 1767 6.01 Rust #5 6.12 11,068 2220 6.11 Rust #4 6.20 11,068 1803 6.20 Swift #3 8.06 11,340 1204 8.06 Swift #2 9.12 11,340 1192 9.12 Swift #9 285.30 14,892 1526 285.29 spectral-norm source secs mem gz cpu secs Rust #6 0.71 11,124 1126 2.84 Rust #7 0.72 11,128 932 2.84 Rust #5 0.72 11,124 1055 2.84 Rust #4 0.72 11,124 817 2.84 Rust #2 0.72 11,124 1110 2.85 Rust 0.72 11,124 1254 2.85 Rust #3 0.78 11,124 1053 3.07 Swift 5.32 14,944 438 5.32 Swift #3 1.43 11,344 601 5.68 mandelbrot source secs mem gz cpu secs Rust #4 1.01 32,380 1295 3.99 Rust #6 1.06 34,120 1332 4.18 Rust #5 1.12 33,868 719 4.41 Rust #3 1.15 13,452 1007 4.58 Swift #7 1.40 46,628 1140 5.57 Rust #7 1.42 32,124 757 5.64 Rust #8 1.42 32,176 763 5.64 Swift #6 1.42 49,544 1141 5.64 Rust 2.05 38,724 868 8.09 Swift 25.99 11,340 394 25.98 Swift #5 7.29 43,012 659 26.91 Swift #3 Bad Output pidigits source secs mem gz cpu secs Rust #4 0.71 11,068 799 0.71 Rust #2 0.88 11,068 1306 0.88 Rust #3 0.88 11,068 1366 0.88 Swift #2 0.88 11,344 600 0.88 Rust 0.89 11,068 1420 0.88 regex-redux source secs mem gz cpu secs Rust #6 1.34 152,724 986 1.80 Rust #5 1.40 204,604 771 1.82 Rust #4 1.43 204,656 765 1.85 Rust 1.46 153,312 804 1.87 Rust #3 1.42 205,228 719 1.88 Rust #2 1.50 153,320 701 1.90 Rust #7 0.78 149,524 2458 1.99 Swift #2 34.87 683,772 671 34.85 Swift 18.89 883,576 715 35.94 Swift #4 18.76 962,572 745 36.82 fasta source secs mem gz cpu secs Rust #7 0.76 11,068 2529 1.52 Rust #3 2.00 11,036 1233 2.00 Swift #2 2.25 11,340 1945 3.05 Rust #5 0.90 11,060 1961 3.08 Rust #2 0.90 11,068 1906 3.16 Rust #4 3.46 123,660 939 3.46 Rust #6 3.50 123,660 955 3.50 Rust #8 0.92 11,068 1946 3.50 Swift 4.51 11,340 1526 4.51 Swift #3 1.39 27,800 2090 4.51 Rust 4.52 11,036 1237 4.52 k-nucleotide source secs mem gz cpu secs Rust #7 2.88 133,236 1578 9.14 Rust #8 3.56 137,632 1543 10.34 Rust #6 2.88 158,788 1691 10.48 Rust #5 4.08 137,648 1739 11.99 Rust #2 6.30 137,548 1347 16.69 Rust #9 6.54 136,008 1841 17.81 Rust #4 6.95 136,744 1749 18.88 Swift #2 13.63 258,044 1367 52.21 Rust 21.93 155,840 1078 65.94 Swift Make Error reverse-complement source secs mem gz cpu secs Rust 0.47 498,844 3040 0.77 Rust #2 0.80 995,004 1330 1.45 Rust #3 0.81 995,004 1097 1.50 Swift 1.85 795,972 1286 2.30 binary-trees source secs mem gz cpu secs Rust #5 1.08 198,984 765 3.82 Rust #2 1.19 200,532 721 4.27 Rust #4 1.28 198,772 756 4.62 Rust #3 1.36 198,464 754 4.93 Rust 2.10 132,828 751 7.39 Swift #5 13.35 735,440 806 39.79 Swift #3 13.06 704,876 862 41.74 Swift #2 13.04 704,780 816 42.00 Swift 19.62 734,844 714 58.29 Swift #4 18.96 704,904 765 60.01 Swift #9 Make Error Swift Swift version 5.8-dev (LLVM 08f7fecaf6cedb8, Swift 24fe6ae8532db5d) Rust 1.67.0 (fc594f156 2023-01-24) LLVM version: 15.0.6 all Swift programs & measurements all Rust programs & measurements