Comparing the String.Create clever method in C# and F# with BenchmarkDotNet
Using String.Create in F# allocates more memory than in C#.
Results for F#
| Method | Mean | Error | StdDev | Gen 0 | Gen 1 | Gen 2 | Allocated |
|---|---|---|---|---|---|---|---|
| StandardReplace | 348.1 ns | 7.03 ns | 6.91 ns | 0.1173 | - | - | 368 B |
| StringCreateFor | 210.8 ns | 4.18 ns | 4.29 ns | 0.0918 | - | - | 288 B |
And C#
| Method | Mean | Error | StdDev | Gen 0 | Gen 1 | Gen 2 | Allocated |
|---|---|---|---|---|---|---|---|
| StandardReplace | 244.3 ns | 3.03 ns | 2.53 ns | 0.1168 | - | - | 368 B |
| StringCreate | 127.9 ns | 2.63 ns | 2.92 ns | 0.0587 | - | - | 184 B |
| StringCreateForEach | 126.7 ns | 2.41 ns | 2.25 ns | 0.0587 | - | - | 184 B |
Using String.Create with F# allocates 288bytes. In C# it is only 184bytes.