如何在后台优化对多个文件的写入

我的程序需要经常将消息写入几个文件。因为它非常耗时，我需要优化它。下面，你可以从我的程序中找到一个摘录，我试图在后台异步写入文件。它似乎有效，但我不确定它是否是最佳实践，因为我不处理任务(这部分是评论)。我不这样做是因为我不想让我的程序等待这些任务完成。简单地说，我希望我的消息尽可能快地写入后台的几个文件。由于这些文件可以被多个线程访问，所以我添加了锁。我使用静态方法是因为这些方法在我的代码中无处不在，我不想实例化这个类，只是为了在文件中到处写一行消息(也许这是错误的)。

================== 类 ==============================================

namespace test
{
    public static class MessageLOG 
    {
    private static string debugFileName         = Settings.DebugLOGfilename;
    private static string logFileName           = Settings.LOGfilename;
    private static object DebuglockOn   = new object();
    private static object LoglockOn     = new object();
    private static StreamWriter DebugSW;
    private static StreamWriter LogSW;
    private static void DebugFile(string message)
    {          
        uint linesCount = 0;
        string _filename = debugFileName;
        if(DebugSW == null && !string.IsNullOrEmpty(_filename))
            DebugSW = new StreamWriter(_filename);

        if(DebugSW != null)                
        {
            lock(DebuglockOn)
            {
                DebugSW.WriteLine(message);
                linesCount++;
                if (linesCount > 10)
                {
                    DebugSW.Flush();
                    linesCount = 0;
                }                        
            }                
        }                
    }
    private static void LogFile(string message)
    {
        uint linesCount = 0;
        string _filename = logFileName;
        if(LogSW == null && !string.IsNullOrEmpty(_filename))
            LogSW = new StreamWriter(_filename);

        if(LogSW != null)                
        {
            lock(LoglockOn)
            {
                LogSW.WriteLine(string.Format("{0} ({1}): {2}", DateTime.Now.ToShortDateString(), DateTime.Now.ToShortTimeString(), message));
                linesCount++;
                if (linesCount > 10)
                {
                    LogSW.Flush();
                    linesCount = 0;
                }
            }                
        }

        public static void LogUpdate(string message)
        {
            ThreadPool.QueueUserWorkItem(new WaitCallback( (x) => LogFile(message)));
            ThreadPool.QueueUserWorkItem(new WaitCallback( (x) => DebugFile(message)));
            ThreadPool.QueueUserWorkItem(new WaitCallback( (x) => Debug.WriteLine(message)));
        }
//This method will be called when the main thread is being closed
        public static void CloseAllStreams()
        {
            if (DebugSW != null)
            {
                DebugSW.Flush();
                DebugSW.Close();
            }
            if (LogSW != null)
            {
                LogSW.Flush();
                LogSW.Close();
            }    
        }
=============== main window ===========
void MainWIndow()
{
... some code ....
MessageLog.LogUpdate("Message text");
...  code cont ....   
MessageLog.CloseAllStreams(); 
}