If OrderBy is used with a value type key and and a default or no comparer is specified, we can use Comparer<TKey>.Default.Compare to avoid the interface dispatch. This optimization can be taken further, but for now it handles a common set of cases. (We can subsequently look into a variety of improvements, such as a cheaper way to implement a stable sort, doing the sort in-place in the buffered output when conditions are ammenable, extending these checks for using the default comparer into chained OrderBy/ThenBy cases, etc.)

[Params(10, 100, 1_000, 1_000_000)]
public int Length { get; set; }

private int[] _values;

[GlobalSetup]
public void Setup() => _values = Enumerable.Range(0, Length).Reverse().ToArray();

[Benchmark]
public int[] OrderByToArray() => _values.OrderBy(i => i).ToArray();