a question about delay time

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C#

.NET

WinForms

When i create a thread to do some work,the thread contains 'while' loop,if the loop don't use thread.sleep method to delay,the window will be very slow.
so the question is how many delay time i decided to use.
for example:
if i use 10ms to delay,the window slow,if i use 100ms to delay,maybe the window will not slow.
different computers have different performance, delay of 100 milliseconds on a different computer operation is not always not slow
so,how many delay time should i decided?

thNcFill = new Thread(new ParameterizedThreadStart(thNcCode));
thNcFill.Start();

        void thNcCode(object oState)
        {
            m_busy = true;
            m_cancelThread = false;
            int iququeNcCount = queueNcCode.Count;

            while (!m_cancelThread)
            {

                if ((iRowIndex == iRowCount) && (iRowIndex > 0))
                {
                    iRowIndex = 0;
                    iRowCount = 0;
                    break;
                }

                try
                {
                    if (iququeNcCount > 0)
                    {
                        string ncCodeContext = queueNcCode.Dequeue();


                        if (ncCodeContext != null)
                        {

                            ncResolver.GetCurrentRow(ncCodeContext, iRowIndex, iRowCount - 1);
                            iRowIndex++;
                        }

                        iququeNcCount--;
                    }

                }
                catch (Exception ncCodeException)
                {
                    if ((ncCodeException as ThreadAbortException) == null)
                    {
                        logTracer.SendTracerMessage(new TracerMessage(TraceType.ERROR, "processing error(rowNumber:" + (iRowIndex + 1).ToString() + "):" + ncCodeException.Message));

                        iRowIndex = 0;
                        iRowCount = 0;
                        Console.WriteLine(DateTime.Now.ToString());
                    }
                    break;
                }
                m_busy = false;
                m_resetEvent.Set();

                System.Threading.Thread.Sleep(10);  //this is the question about delay time
            }
        }