I often see in pull request a mutation of a list. I always said that this is not a good idea but these are only my words maybe with some articles to prove my rights. This is why I decided to create some benchmarks to show that Mutation is not a good idea. Below you could find results from the benchmarks.
BenchmarkDotNet=v0.11.0, OS=Windows 10.0.17134.112 (1803/April2018Update/Redstone4)
Intel Core i7-7700HQ CPU 2.80GHz (Kaby Lake), 1 CPU, 8 logical and 4 physical cores
Frequency=2742186 Hz, Resolution=364.6726 ns, Timer=TSC
.NET Core SDK=2.1.301
[Host] : .NET Core 2.1.1 (CoreCLR 4.6.26606.02, CoreFX 4.6.26606.05), 64bit RyuJIT [AttachedDebugger]
Job-HVYYGX : .NET Core 2.1.1 (CoreCLR 4.6.26606.02, CoreFX 4.6.26606.05), 64bit RyuJIT
IterationCount=10 LaunchCount=2 WarmupCount=5
| Method | Mean | Error | StdDev | Gen 0 | Gen 1 | Gen 2 | Allocated |
|---|---|---|---|---|---|---|---|
| WithMutationTestSmall | 26.06 us | 0.2547 us | 0.2831 us | 3.9978 | - | - | 12.3 KB |
| WithMutationTestMedium | 256.99 us | 5.3920 us | 6.2094 us | 37.5977 | - | - | 117.78 KB |
| WithMutationTestBig | 3,553.16 us | 47.0130 us | 52.2549 us | 210.9375 | 97.6563 | 39.0625 | 1272.02 KB |
| WithPredefinedSizeTestSmall | 24.65 us | 0.2059 us | 0.2289 us | 3.5400 | - | - | 10.96 KB |
| WithPredefinedSizeTestMedium | 247.12 us | 1.6088 us | 1.8527 us | 35.1563 | - | - | 109.4 KB |
| WithPredefinedSizeTestBig | 2,608.53 us | 31.7756 us | 35.3185 us | 191.4063 | 93.7500 | - | 1093.77 KB |
| WithLazyEvaluationTestSmall | 27.37 us | 0.1751 us | 0.2017 us | 4.0283 | - | - | 12.41 KB |
| WithLazyEvaluationTestMedium | 277.71 us | 7.9785 us | 9.1881 us | 38.0859 | 0.4883 | - | 117.89 KB |
| WithLazyEvaluationTestBig | 3,718.37 us | 22.2728 us | 23.8316 us | 210.9375 | 97.6563 | 39.0625 | 1272.1 KB |
| WithSelectTestSmall | 24.45 us | 0.0937 us | 0.0963 us | 3.6011 | - | - | 11.07 KB |
| WithSelectTestMediumSmall | 246.86 us | 2.6934 us | 3.1017 us | 35.1563 | - | - | 109.51 KB |
| WithSelectTestBig | 2,570.04 us | 19.1668 us | 22.0725 us | 191.4063 | 93.7500 | - | 1093.88 KB |