Linq Where + First & First benchmark. https://twitter.com/badamczewski01/status/1454762216083836928

LinqWhereFirst.cs

BenchmarkRunner.Run<BenchmarkLinqWhereFirst>();

[BenchmarkDotNet.Attributes.MemoryDiagnoser]
public class BenchmarkLinqWhereFirst
{
    private readonly int[] data;
    public BenchmarkLinqWhereFirst()
    {
        data = Enumerable.Range(1, 1000).ToArray();
    }
    [Benchmark]
    public int WhereFirst() => data.Where(x => x > 100).First();

    [Benchmark]
    public void First() => data.First(x => x > 100);
}

LinqWhereFirst_DotNet5_Result.txt

// Validating benchmarks:
Assembly LINQPadQuery, Version=1.0.0.213, Culture=neutral, PublicKeyToken=null is located in temp. If you are running benchmarks from xUnit you need to disable shadow copy. It's not supported by design.
// ***** BenchmarkRunner: Start   *****
// * Summary *

BenchmarkDotNet=v0.13.1, OS=Windows 10.0.22000
AMD Ryzen 9 5900X, 1 CPU, 24 logical and 12 physical cores
.NET SDK=6.0.100-rc.2.21505.57
  [Host] : .NET 5.0.11 (5.0.1121.47308), X64 RyuJIT


|     Method |     Mean |   Error |  StdDev |  Gen 0 | Allocated |
|----------- |---------:|--------:|--------:|-------:|----------:|
| WhereFirst | 166.9 ns | 0.52 ns | 0.48 ns | 0.0029 |      48 B |
|      First | 404.8 ns | 1.09 ns | 0.91 ns | 0.0019 |      32 B |

// * Legends *
  Mean      : Arithmetic mean of all measurements
  Error     : Half of 99.9% confidence interval
  StdDev    : Standard deviation of all measurements
  Gen 0     : GC Generation 0 collects per 1000 operations
  Allocated : Allocated memory per single operation (managed only, inclusive, 1KB = 1024B)
  1 ns      : 1 Nanosecond (0.000000001 sec)

// * Diagnostic Output - MemoryDiagnoser *


// ***** BenchmarkRunner: End *****
// ** Remained 0 benchmark(s) to run **
Run time: 00:00:38 (38.6 sec), executed benchmarks: 2

Global total time: 00:00:38 (38.64 sec), executed benchmarks: 2
// * Artifacts cleanup *

LinqWhereFirst_DotNet6_Result.txt

// Validating benchmarks:
Assembly LINQPadQuery, Version=1.0.0.4, Culture=neutral, PublicKeyToken=null is located in temp. If you are running benchmarks from xUnit you need to disable shadow copy. It's not supported by design.
// ***** BenchmarkRunner: Start   *****
// * Summary *

BenchmarkDotNet=v0.13.1, OS=Windows 10.0.22000
AMD Ryzen 9 5900X, 1 CPU, 24 logical and 12 physical cores
.NET SDK=6.0.100-rc.2.21505.57
  [Host] : .NET 6.0.0 (6.0.21.48005), X64 RyuJIT


|     Method |     Mean |   Error |  StdDev |  Gen 0 | Allocated |
|----------- |---------:|--------:|--------:|-------:|----------:|
| WhereFirst | 182.3 ns | 1.60 ns | 1.42 ns | 0.0029 |      48 B |
|      First | 444.8 ns | 3.26 ns | 2.73 ns | 0.0019 |      32 B |

// * Legends *
  Mean      : Arithmetic mean of all measurements
  Error     : Half of 99.9% confidence interval
  StdDev    : Standard deviation of all measurements
  Gen 0     : GC Generation 0 collects per 1000 operations
  Allocated : Allocated memory per single operation (managed only, inclusive, 1KB = 1024B)
  1 ns      : 1 Nanosecond (0.000000001 sec)

// * Diagnostic Output - MemoryDiagnoser *


// ***** BenchmarkRunner: End *****
// ** Remained 0 benchmark(s) to run **
Run time: 00:00:43 (43.05 sec), executed benchmarks: 2

Global total time: 00:00:43 (43.06 sec), executed benchmarks: 2
// * Artifacts cleanup *