Wrote this quick little performance testing harness. Guessing this is a C# right of passage kind of thing.

measureme.cs

public static void MeasureMe(Action action, int count=100, int warmup = 10, int runs = 1,string messageFormat = "It took {0}ms to do this.")
{
	Enumerable.Range(0, warmup).Each(i =>
	{
		action();
	});

	Enumerable.Range(0, runs).Each(r =>
	{
		var watch = new Stopwatch();
		watch.Start();
		Enumerable.Range(0, count).Each(i =>
		{
			action();
		});
		watch.Stop();
		var output = String.Format(messageFormat, watch.ElapsedMilliseconds);
		Console.WriteLine(output);
	});
}

Example usage:

var menuSource = Container.GetInstance<MyWorkMenuSource>();
var menuSource2 = Container.GetInstance<MyWorkMenuSource2>();

MeasureMe(() =>
{
    menuSource.GetMenu();
}, count:100, runs:3, messageFormat:"Original:{0}");

MeasureMe(() =>
{
    menuSource2.GetMenu();
}, count: 100, runs: 3, messageFormat: "Replacement:{0}");