Java versus C# .NET 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. binary-trees source secs mem gz busy cpu load Java 2.48 1,722,848 835 7.88 98% 75% 71% 74% C# .NET 4.81 1,881,564 676 15.47 81% 74% 83% 83% fasta source secs mem gz busy cpu load Java 1.21 44,620 2543 3.58 89% 75% 65% 68% C# .NET 1.21 152,684 1691 4.58 96% 97% 92% 93% pidigits source secs mem gz busy cpu load Java 0.93 36,552 764 0.98 2% 3% 1% 99% C# .NET 0.92 35,404 977 0.96 98% 3% 2% 1% reverse-complement source secs mem gz busy cpu load Java 1.54 670,924 2183 3.51 46% 56% 48% 79% C# .NET 1.50 950,648 1310 4.29 93% 63% 93% 38% fannkuch-redux source secs mem gz busy cpu load Java 10.64 35,192 1282 41.91 99% 98% 99% 97% C# .NET 8.40 30,848 1225 33.29 99% 100% 99% 99% mandelbrot source secs mem gz busy cpu load Java 4.15 69,136 796 16.29 98% 99% 98% 99% C# .NET 3.14 64,940 1974 12.30 99% 98% 97% 97% n-body source secs mem gz busy cpu load Java 6.74 35,844 1489 6.82 1% 100% 1% 0% C# .NET 4.83 32,756 1704 4.85 0% 0% 0% 100% k-nucleotide source secs mem gz busy cpu load Java 4.98 356,904 1812 16.25 78% 76% 96% 76% C# .NET 3.29 182,860 2044 11.20 99% 86% 66% 90% spectral-norm source secs mem gz busy cpu load Java 1.63 39,304 756 6.22 95% 97% 95% 95% C# .NET 0.82 35,048 764 2.99 89% 96% 89% 89% regex-redux source secs mem gz busy cpu load Java 5.58 985,696 929 18.26 81% 77% 84% 85% C# .NET 1.42 280,892 1869 2.69 30% 39% 86% 35% Java openjdk 16 2021-03-16 OpenJDK Runtime Environment (build 16+36-2231) OpenJDK 64-Bit Server VM (build 16+36-2231, mixed mode, sharing) C# .NET .NET SDK 5.0.201 Host Version: 5.0.4; Commit: f27d337295 <ServerGarbageCollection>true</ServerGarbageCollection> all Java programs & measurements all C# .NET programs & measurements