‘as’ versus type casting

Prefix casting vs as casting

Stopwatch s = new Stopwatch();
            s.Start();
            for (int i = 0; i < 100000000; i++)
            {
                object myClass = new CNDSegment();
                ((CNDSegment)myClass).Method1();
            }
            s.Stop();
            Console.WriteLine(String.Format("Time taken by prefix casting is {0} milliseconds", s.ElapsedMilliseconds));
            s.Reset();
            s.Start();
            for (int i = 0; i < 100000000; i++)
            {
                object myClass = new CNDSegment();
                (myClass as CNDSegment).Method1();
            }
            s.Stop();
            Console.WriteLine(String.Format("Time taken by as casting and typeof method {0} milliseconds", s.ElapsedMilliseconds));

            Console.ReadLine();

Time taken by prefix casting is 1406 milliseconds
Time taken by as casting and typeof method 1338 milliseconds

Read this:
http://www.codeproject.com/Articles/8052/Type-casting-impact-over-execution-performance-in#_rating
http://gen5.info/q/2008/06/13/prefix-casting-versus-as-casting-in-c/