在(几乎)任何编程语言中，等待基本上有3种选择:

Loose waiting Executing thread blocks for given time (= does not consume processing power) No processing is possible on blocked/waiting thread Not so precise Tight waiting (also called tight loop) processor is VERY busy for the entire waiting interval (in fact, it usually consumes 100% of one core's processing time) Some actions can be performed while waiting Very precise Combination of previous 2 It usually combines processing efficiency of 1. and preciseness + ability to do something of 2.

为1。c#中的松散等待:

Thread.Sleep(numberOfMilliseconds);

然而，windows线程调度器导致Sleep()的准确性在15ms左右(所以Sleep可以很容易地等待20ms，即使计划只等待1ms)。

为2。c#中的紧等待是:

Stopwatch stopwatch = Stopwatch.StartNew();
while (true)
{
    //some other processing to do possible
    if (stopwatch.ElapsedMilliseconds >= millisecondsToWait)
    {
        break;
    }
}

我们也可以使用DateTime。现在或其他方式的时间测量，但秒表是快得多(这将真正成为在紧循环)。

为3。——组合:

Stopwatch stopwatch = Stopwatch.StartNew();
while (true)
{
    //some other processing to do STILL POSSIBLE
    if (stopwatch.ElapsedMilliseconds >= millisecondsToWait)
    {
        break;
    }
    Thread.Sleep(1); //so processor can rest for a while
}

这段代码会定期阻塞线程1ms(或者稍微多一点，这取决于操作系统线程调度)，所以处理器在阻塞期间并不繁忙，代码也不会消耗处理器100%的功耗。其他处理仍然可以在阻塞之间执行(例如:更新UI，处理事件或做交互/通信之类的事情)。

从.NET Framework 4.5开始，你可以使用:

using System.Threading.Tasks;

Task.Delay(50).Wait();   // wait 50ms

在Windows中无法指定确切的睡眠时间。你需要一个实时的操作系统。最好的方法是指定一个最小睡眠时间。然后由调度器在此之后唤醒线程。永远不要在GUI线程上调用. sleep()。

Thread.Sleep(50);

在指定的时间内，操作系统不会调度线程执行。该方法将线程的状态更改为包含WaitSleepJoin。

此方法不执行标准的COM和SendMessage抽取。 如果您需要在具有STAThreadAttribute的线程上休眠，但又希望执行标准COM和SendMessage泵送，请考虑使用指定超时间隔的Join方法的一个重载。

Thread.Join

两全其美:

using System.Runtime.InteropServices;

    [DllImport("winmm.dll", EntryPoint = "timeBeginPeriod", SetLastError = true)]
    private static extern uint TimeBeginPeriod(uint uMilliseconds);

    [DllImport("winmm.dll", EntryPoint = "timeEndPeriod", SetLastError = true)]
    private static extern uint TimeEndPeriod(uint uMilliseconds);
    /**
     * Extremely accurate sleep is needed here to maintain performance so system resolution time is increased
     */
    private void accurateSleep(int milliseconds)
    {
        //Increase timer resolution from 20 miliseconds to 1 milisecond
        TimeBeginPeriod(1);
        Stopwatch stopwatch = new Stopwatch();//Makes use of QueryPerformanceCounter WIN32 API
        stopwatch.Start();

        while (stopwatch.ElapsedMilliseconds < milliseconds)
        {
            //So we don't burn cpu cycles
            if ((milliseconds - stopwatch.ElapsedMilliseconds) > 20)
            {
                Thread.Sleep(5);
            }
            else
            {
                Thread.Sleep(1);
            }
        }

        stopwatch.Stop();
        //Set it back to normal.
        TimeEndPeriod(1);
    }

既然现在你有了async/await特性，那么最好的睡眠50ms的方法就是使用Task。延迟:

async void foo()
{
    // something
    await Task.Delay(50);
}

或者如果你的目标是。net 4(使用VS2010的Async CTP 3或Microsoft.Bcl.Async)，你必须使用:

async void foo()
{
    // something
    await TaskEx.Delay(50);
}

这样你就不会阻塞UI线程。