C gcc versus C clang 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 gcc #6 2.16 19,516 1582 8.53 C clang #6 2.18 19,788 1582 8.63 C clang #4 13.08 19,660 1190 13.08 C gcc #4 14.20 19,516 1190 14.20 C gcc #5 6.91 19,644 917 27.13 C clang #5 8.31 19,784 917 32.84 C clang #2 8.85 19,660 1563 34.65 C clang #3 34.83 19,788 574 34.83 C clang 37.30 19,660 514 37.29 C gcc #3 39.57 19,516 574 39.57 C gcc 42.24 19,640 514 42.24 C gcc #2 11.16 19,644 1563 43.66 n-body source secs mem gz cpu secs C gcc #9 2.10 19,520 1639 2.10 C clang #9 2.19 19,684 1639 2.19 C gcc #8 3.70 19,520 1398 3.69 C gcc #4 4.30 19,520 1496 4.30 C clang #4 4.84 19,808 1496 4.84 C clang #5 4.85 19,808 1436 4.85 C gcc #6 4.96 19,520 1186 4.96 C gcc 5.18 19,520 1179 5.18 C gcc #2 5.18 19,520 1270 5.18 C gcc #3 5.24 19,520 1214 5.24 C gcc #5 5.41 19,648 1436 5.41 C clang #6 5.44 19,684 1186 5.44 C clang #8 5.56 19,680 1398 5.56 C clang #2 5.57 19,684 1270 5.57 C clang 5.65 19,684 1179 5.65 C clang #3 6.13 19,812 1214 6.13 C clang #7 6.70 19,812 1250 6.70 C gcc #7 6.81 19,520 1250 6.81 spectral-norm source secs mem gz cpu secs C clang #6 0.39 19,812 1203 1.55 C gcc #6 0.41 19,760 1203 1.61 C gcc #5 0.72 19,520 576 2.84 C gcc #7 0.73 19,520 906 2.84 C gcc #4 0.72 19,520 1145 2.84 C clang #8 0.72 19,684 941 2.87 C clang #5 0.72 19,812 576 2.87 C clang #4 0.73 19,812 1145 2.89 C gcc 5.39 19,520 390 5.39 C clang 5.39 19,684 390 5.39 C gcc #3 1.43 19,520 470 5.68 C clang #3 1.44 19,812 470 5.74 C clang #7 2.24 19,684 906 8.92 C gcc #8 Make Error mandelbrot source secs mem gz cpu secs C gcc #6 1.28 33,280 1141 5.11 C clang #9 1.29 34,432 700 5.12 C clang #8 1.53 34,688 788 6.10 C gcc #8 1.63 33,536 788 6.30 C gcc #4 3.48 33,152 805 13.85 C gcc 3.49 32,896 828 13.88 C gcc #7 3.49 33,152 1000 13.89 C clang 3.48 33,280 828 13.89 C clang #4 3.49 34,176 805 13.92 C gcc #3 3.54 32,768 769 14.07 C clang #7 3.57 34,048 1000 14.16 C clang #3 3.57 33,152 769 14.23 C gcc #9 4.22 33,280 700 16.30 C gcc #2 24.97 19,520 412 24.97 C clang #2 25.43 19,680 412 25.43 C clang #6 Make Error pidigits source secs mem gz cpu secs C gcc #2 0.81 19,520 422 0.81 C clang #2 0.81 19,684 422 0.81 C clang 0.88 19,684 459 0.88 C gcc 0.88 19,520 459 0.88 regex-redux source secs mem gz cpu secs C gcc #5 0.80 152,388 1403 2.03 C clang #5 0.81 154,520 1403 2.80 C clang #2 3.21 103,424 1121 3.21 C gcc #2 3.23 103,296 1121 3.23 C gcc #4 0.96 152,256 1237 3.27 C gcc #3 1.72 103,680 1273 3.29 C clang #4 0.96 154,248 1237 3.72 C clang #3 1.76 105,856 1273 4.33 fasta source secs mem gz cpu secs C gcc #9 0.78 19,520 1469 0.78 C clang #9 0.78 19,804 1469 0.78 C clang #5 1.08 19,672 1286 1.08 C gcc #5 1.24 19,520 1286 1.24 C clang #8 2.41 19,680 1299 2.41 C gcc #6 0.93 19,648 1936 2.73 C gcc #8 2.79 19,520 1299 2.79 C clang #6 1.01 19,808 1936 2.98 C gcc #4 3.02 19,520 1244 3.02 C gcc #2 0.83 19,520 2270 3.26 C gcc #7 0.85 19,648 2018 3.29 C clang #2 0.83 19,676 2276 3.31 C clang #7 0.86 19,676 2018 3.31 C gcc 3.74 19,520 1209 3.73 C clang #3 4.48 19,676 825 4.48 C gcc #3 4.49 19,520 825 4.48 C clang #4 Make Error C clang Make Error k-nucleotide source secs mem gz cpu secs C gcc 3.80 130,432 1512 12.64 C clang 6.22 129,140 1512 13.57 reverse-complement source secs mem gz cpu secs C gcc #7 0.43 499,872 1899 0.58 C clang #7 0.43 499,876 1899 0.59 C clang #8 0.46 500,004 1551 0.69 C gcc #8 0.50 499,872 1551 0.86 C gcc #6 0.96 703,064 828 1.37 C gcc #5 1.50 994,176 654 1.50 C gcc #2 1.05 994,432 757 1.55 C clang #2 1.13 994,432 757 1.64 C clang #5 2.04 994,176 654 2.04 C gcc #4 3.66 500,480 716 3.66 C clang #4 3.77 500,480 716 3.77 C clang #6 0.98 706,852 828 3.89 binary-trees source secs mem gz cpu secs C gcc #2 1.51 169,088 816 4.17 C gcc #3 1.89 134,400 842 4.59 C clang #2 1.64 170,112 816 5.26 C clang #3 1.82 134,144 842 5.67 C clang 17.12 264,192 660 17.11 C gcc 20.83 264,192 660 20.83 C gcc #5 8.27 351,232 914 30.31 C clang #5 8.87 351,360 914 31.91 C gcc 13.2.0-4ubuntu3 C clang Ubuntu clang version 17.0.2 all C gcc programs & measurements all C clang programs & measurements