List - ConvertAll vs Select Benchmark

ConvertAllvsSelectBenchmark.cs

using BenchmarkDotNet.Attributes;

namespace Benchmark.Tests
{
    [MemoryDiagnoser]
    public class ConvertAllvsSelectBenchmark
    {
        [Params(10, 100)]
        public int Iterations { get; set; }

        public List<Apple> Items { get; set; } = new();

        [GlobalSetup]
        public void GlobalSetup()
        {
            Items.AddRange(Enumerable.Range(0, Iterations).Select(_ => new Apple()));
        }

        [Benchmark]
        public void ConvertAllTest()
        {
            var items = Items.ConvertAll(s => s.Color);
        }

        [Benchmark]
        public void SelectTest()
        {
            var items = Items.Select(s => s.Color).ToList();
        }
    }
    
    public class Apple
    {
        public string Color { get; set; } = "Red";
        public string Origin { get; set; } = "Not Specified";

        public void ProcessCost() { }
    }
}

Test on .NET 6

.NET SDK=6.0.100-rc.1.21463.6
[Host] : .NET 6.0.0 (6.0.21.45113), X64 RyuJIT
DefaultJob : .NET 6.0.0 (6.0.21.45113), X64 RyuJIT

Method	Iterations	Mean	Error	StdDev	Gen 0	Allocated
ConvertAllTest	10	50.90 ns	1.028 ns	1.143 ns	0.0081	136 B
SelectTest	10	68.60 ns	1.401 ns	1.499 ns	0.0124	208 B
ConvertAllTest	100	361.99 ns	7.194 ns	8.564 ns	0.0510	856 B
SelectTest	100	425.84 ns	8.231 ns	7.699 ns	0.0553	928 B
`