Swift versus C++ g++ 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 C++ g++ #6 3.25 19,788 1535 12.89 C++ g++ #7 13.93 19,660 1156 13.93 C++ g++ #5 7.97 19,788 987 31.14 Swift 33.85 19,660 457 33.85 Swift #3 8.58 19,660 1103 33.96 C++ g++ #3 36.80 19,660 600 36.80 C++ g++ #4 9.47 19,660 1445 37.11 C++ g++ #2 9.82 19,656 1446 38.58 C++ g++ 10.59 19,660 1065 41.61 n-body source secs mem gz cpu secs C++ g++ #0 2.14 19,676 1933 2.14 C++ g++ #7 3.97 19,804 1815 3.97 C++ g++ #2 4.20 19,676 1884 4.19 C++ g++ #3 5.30 19,804 1402 5.30 C++ g++ #9 5.43 19,676 1536 5.43 C++ g++ #4 5.44 19,804 1434 5.44 Swift #4 5.49 19,680 1361 5.49 Swift #5 5.51 19,812 1372 5.51 Swift #7 5.52 19,684 1333 5.52 Swift #6 5.97 19,680 1200 5.97 Swift #8 5.99 19,808 1688 5.99 C++ g++ #5 6.01 19,676 1544 6.00 C++ g++ 6.49 19,676 1666 6.49 C++ g++ #8 6.57 19,676 1524 6.57 C++ g++ #6 6.89 19,676 1674 6.89 Swift #2 9.55 19,684 1198 9.55 Swift #3 202.89 19,680 1210 202.89 Swift #9 287.28 19,684 1532 287.27 spectral-norm source secs mem gz cpu secs C++ g++ #6 0.72 19,812 1050 2.84 C++ g++ #5 1.32 19,684 1050 5.25 Swift 5.32 19,684 444 5.32 C++ g++ 5.36 19,684 459 5.36 Swift #3 1.43 19,684 607 5.69 C++ g++ #8 1.52 19,684 1284 6.04 mandelbrot source secs mem gz cpu secs C++ g++ 0.89 34,944 1797 3.46 C++ g++ #4 0.89 35,200 3554 3.47 C++ g++ #6 0.98 35,072 1014 3.89 Swift #7 1.34 47,104 1147 5.30 Swift #6 1.45 50,176 1147 5.73 C++ g++ #0 2.35 35,328 2752 9.28 C++ g++ #8 4.79 35,072 749 13.12 C++ g++ #5 13.33 34,688 596 13.33 C++ g++ #9 3.50 35,200 732 13.49 C++ g++ #7 3.49 35,072 1023 13.90 C++ g++ #2 16.90 34,560 700 16.90 Swift 26.40 19,680 400 26.40 Swift #5 7.21 43,520 665 26.95 C++ g++ #3 27.26 19,804 421 27.25 Swift #3 Bad Output pidigits source secs mem gz cpu secs C++ g++ #5 0.86 19,804 804 0.86 Swift #2 0.88 19,684 606 0.88 C++ g++ #4 0.88 19,804 521 0.88 regex-redux source secs mem gz cpu secs C++ g++ #6 1.15 276,276 2856 2.18 C++ g++ #2 2.84 212,776 706 3.60 C++ g++ 3.62 212,180 662 3.62 C++ g++ #5 3.86 215,556 859 4.54 C++ g++ #3 12.41 217,580 859 17.91 Swift #2 41.76 684,640 678 41.75 Swift 24.13 889,972 721 42.70 Swift #4 20.41 1,060,208 751 44.32 C++ g++ #4 Make Error fasta source secs mem gz cpu secs C++ g++ #8 0.76 19,792 2758 1.51 C++ g++ #2 1.81 19,668 1129 1.81 C++ g++ 1.90 19,664 1064 1.90 C++ g++ #3 2.62 19,664 1311 2.62 C++ g++ #4 3.32 19,664 1291 3.32 Swift #2 2.18 19,680 1952 3.83 C++ g++ #6 1.05 19,668 2326 3.85 C++ g++ #5 1.05 19,668 2345 3.88 Swift 5.15 19,676 1533 5.15 Swift #3 2.14 29,584 2097 5.26 C++ g++ #7 Make Error k-nucleotide source secs mem gz cpu secs C++ g++ #2 1.97 156,504 1634 5.87 C++ g++ #3 4.19 165,592 1280 13.77 C++ g++ 6.90 757,080 1452 14.68 Swift #2 14.51 259,048 1373 55.29 Swift Make Error reverse-complement source secs mem gz cpu secs C++ g++ #2 0.70 499,840 2099 0.70 Swift 1.88 796,840 1293 2.30 C++ g++ #6 3.20 1,517,660 1827 4.22 C++ g++ 6.56 980,060 599 6.56 C++ g++ #5 35.10 771,556 704 35.10 C++ g++ #3 Bad Output binary-trees source secs mem gz cpu secs C++ g++ #7 0.95 201,400 896 3.30 C++ g++ #5 1.14 200,660 891 3.98 C++ g++ #9 1.72 135,936 815 4.46 C++ g++ #6 1.88 266,112 851 4.47 C++ g++ #3 1.88 265,600 951 4.72 C++ g++ #8 2.18 265,984 826 5.11 C++ g++ 2.65 2,040,792 760 9.07 C++ g++ #2 21.51 265,856 514 21.51 Swift #5 13.79 736,000 813 40.99 Swift #3 13.33 705,408 868 43.00 Swift #2 13.28 705,280 822 43.28 Swift 20.15 735,488 720 59.68 Swift #4 19.49 705,536 772 62.34 C++ g++ #4 Make Error Swift #9 Make Error Swift Swift version 5.10 (swift-5.10-RELEASE) C++ g++ Ubuntu 13.2.0-4ubuntu3 all Swift programs & measurements all C++ g++ programs & measurements