CPU usage increases for Empty Infinite While loop

Question

Can anyone explain me why the following Infinite loop takes a lot of CPU usage (CPU usage has increased upto 50% if total core is 2 and 100% if total CPU core is just 1)

But if I un-comment the line it reduces to 1 or 2 CPU usage?

    public class Program
    {
        public static void Main(string[] args)
        {
            while (true)
            {
                //Console.WriteLine("hello..");
            }
        }
    }

Answer 1

Console.WriteLine is a blocking (interruptable) I/O call, so other things can happen while the processor is blocked on I/O. In fact, it spends significantly more time blocked on I/O than it does evaluating the trivial condition true and jumping!

Without the writeline call, your processor is completely busy and cannot be interrupted.

Try replacing Console.WriteLine with something like int x = 1, or anything that does not block. This should behave like the empty body case.