_Results.md

BenchmarkDotNet=v0.12.1, OS=Windows 10.0.18363.778 (1909/November2018Update/19H2)
Intel Core i7-8850H CPU 2.60GHz (Coffee Lake), 1 CPU, 12 logical and 6 physical cores
  [Host]     : .NET Framework 4.8 (4.8.4150.0), X64 RyuJIT
  DefaultJob : .NET Framework 4.8 (4.8.4150.0), X64 RyuJIT

Method	Mean	Error	StdDev	Median	Ratio	RatioSD	Gen 0	Gen 1	Gen 2	Allocated
Linq_GetType	38.157 ns	0.7820 ns	2.1540 ns	37.740 ns	1.00	0.00	0.0068	-	-	32 B
Linq_IsOperator	38.333 ns	0.7773 ns	1.1394 ns	38.099 ns	1.01	0.06	0.0068	-	-	32 B
Linq_OfTypeAny	139.816 ns	2.7576 ns	4.2933 ns	140.143 ns	3.70	0.24	0.0186	-	-	88 B
ForEach_GetType	3.600 ns	0.0484 ns	0.0404 ns	3.583 ns	0.10	0.01	-	-	-	-
ForEach_IsOperator	3.561 ns	0.1012 ns	0.1165 ns	3.568 ns	0.09	0.01	-	-	-	-
For_GetType	3.608 ns	0.0665 ns	0.0590 ns	3.632 ns	0.10	0.01	-	-	-	-
For_IsOperator	4.241 ns	0.1123 ns	0.2918 ns	4.130 ns	0.11	0.01	-	-	-	-

ConsoleApp91.csproj

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net48</TargetFramework>
    <LangVersion>latest</LangVersion>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="BenchmarkDotNet" Version="0.12.1" />
  </ItemGroup>

</Project>

Program.cs

using BenchmarkDotNet.Attributes;
using BenchmarkDotNet.Running;
using System;
using System.Linq;

namespace ConsoleApp91
{
    class Program
    {
        static void Main(string[] args)
        {
            BenchmarkRunner.Run<Tests>();
        }
    }

    [MemoryDiagnoser]
    public class Tests
    {
        static readonly object[] _values = new object[]
        {
            123,
            DateTime.UtcNow,
            "abc"
        };

        [Benchmark]
        public bool Linq_GetType()
        {
            return _values.Any(x => x.GetType() == typeof(string));
        }

        [Benchmark]
        public bool Linq_IsOperator()
        {
            return _values.Any(x => x is string);
        }

        [Benchmark]
        public bool Linq_OfTypeAny()
        {
            return _values.OfType<string>().Any();
        }

        [Benchmark]
        public bool ForEach_GetType()
        {
            return Test(_values);

            static bool Test(object[] values)
            {
                foreach (var value in _values)
                {
                    if (value.GetType() == typeof(string))
                    {
                        return true;
                    }
                }
                return false;
            }
        }

        [Benchmark]
        public bool ForEach_IsOperator()
        {
            return Test(_values);
            static bool Test(object[] values)
            {
                foreach (var value in _values)
                {
                    if (value is string)
                    {
                        return true;
                    }
                }
                return false;
            }
        }

        [Benchmark]
        public bool For_GetType()
        {
            var length = _values.Length;
            for (var i = 0; i < length; i++)
            {
                var value = _values[i];
                if (value.GetType() == typeof(string))
                {
                    return true;
                }
            }
            return false;
        }

        [Benchmark]
        public bool For_IsOperator()
        {
            var length = _values.Length;
            for (var i = 0; i < length; i++)
            {
                var value = _values[i];
                if (value is string)
                {
                    return true;
                }
            }
            return false;
        }
    }
}