Comparing results of Nested Property/Field extraction via Reflection or Expression Tree; testing in LinqPad -- from http://stackoverflow.com/questions/536932/how-to-create-expression-tree-lambda-for-a-deep-property-from-a-string

ExtensionMethods.cs

	public static class ObjectExtensions {
		public static object ReflectValue(this object o, string path) {
			// http://stackoverflow.com/a/4474015/1037948
			return path.Split('.').Aggregate(o, (current, component) => {
				var property = current.GetType().GetProperty(component);
				if(null == property) {
					var field = current.GetType().GetField(component);
					if(null == field) return null;
					return field.GetValue(current);
				}
				return property.GetValue(current, null);
			});
		}

		public static Func<TObj, TValue> ExpressValue<TObj, TValue>(this TObj o, string fieldname) {
			// simplified from example - http://marcgravell.blogspot.com/2008/10/express-yourself.html
			// modified for nested properties via http://stackoverflow.com/questions/13613648/nested-property-in-expression-tree and http://stackoverflow.com/a/537189/1037948

			// alias to model
			var m = Expression.Parameter(typeof(TObj), "m");

			// the model property we want
			/*Member*/Expression expr = m;

			// break up nested property
			expr = fieldname.Contains(".")
				? fieldname.Split('.').Aggregate(expr, Expression.PropertyOrField)
				: Expression.PropertyOrField(m, fieldname);

			return Expression.Lambda<Func<TObj, TValue>>(expr, m).Compile();
		}
	}

linqpadextensions.cs

	/// <summary> Performance check -- how long do X repetitions of a task take?</summary>
	public static long Perf(this string reportTitle, Action<int> task, int repetitions = 10000) {
		// http://stackoverflow.com/questions/28637/is-datetime-now-the-best-way-to-measure-a-functions-performance
		Stopwatch sw = Stopwatch.StartNew();

		for (int i = 0; i < repetitions; i++) {
			task(i);
		}

		sw.Stop();
		string.Format("{0} ticks elapsed ({1} ms)", sw.Elapsed.Ticks, sw.Elapsed.TotalMilliseconds).Dump(string.Format("{0} ({1}x)", reportTitle, repetitions));
		return sw.Elapsed.Ticks;
	}

ReflectVsExpress.cs

void Main()
{
	var t1 = Foo.Create(1);

	var field = "Sub.Sub.Sub.ID.N";
	string.Format("Reflect {0}", field).Perf(n => testReflect(t1, field, false));
	string.Format("Express {0}", field).Perf(n => testExpress(t1, field, false));

	t1.Dump("Test Foo 1");
	
	testReflect(t1, "ID.N", true);
	testReflect(t1, "Sub.ID.N", true);
	testReflect(t1, "Sub.Sub.ID.N", true);
	testReflect(t1, "Sub.Sub.Sub.ID.N", true);
	
	testExpress(t1, "ID.N", true);
	testExpress(t1, "Sub.ID.N", true);
	testExpress(t1, "Sub.Sub.ID.N", true);
	testExpress(t1, "Sub.Sub.Sub.ID.N", true);
	
	
}
	// Define other methods and classes here
	void testReflect(object o, string property, bool isDump = false) {
		var p = o.ReflectValue(property);
		if(isDump) p.Dump("Reflect " + property);
	}
	void testExpress(Foo o, string property, bool isDump = false) {
		var p = o.ExpressValue<Foo, string>(property)(o);
		if(isDump) p.Dump("Express " + property);
	}

	public struct Iota
	{
		public string N;
		public int ID;
		public Iota(string n, int id) { this.N = n; this.ID = id; }
		public static Iota Create(int i = 0) { var t = (int)(DateTime.UtcNow.Ticks - 621355968000000000) + i; return new Iota("" + (char)((t%26) + 'a'), t); } 
	}
	public struct Foo
	{
		public string N;
		public Bar Sub;
		public Iota ID;
		public Foo(string n, Bar b, Iota id) { this.N = n; this.ID = id; this.Sub = b; }
		public static Foo Create(int n)
		{
			return new Foo("foo" + n, new Bar("bar" + n, new Baz("baz" + n, new Fon("fon" + n, Iota.Create(n)), Iota.Create(n + 1)), Iota.Create(n + 2)), Iota.Create(n+3));
		}
	}
	public struct Bar
	{
		public string N;
		public Baz Sub;
		public Iota ID;
		public Bar(string n, Baz b, Iota id) { this.N = n; this.ID = id; this.Sub = b; }
	}
	public struct Baz
	{
		public string N;
		public Fon Sub;
		public Iota ID;
		public Baz(string n, Fon b, Iota id) { this.N = n; this.ID = id; this.Sub = b; }
	}
	public struct Fon
	{
		public string N;
		public Iota ID;
		public Fon(string n, Iota id) { this.N = n; this.ID = id; }
	}