C#处理海量数据效率问题

C# code:

private void DoHandler()
{
string path;

DisplayProcessStatus("正在校验用户输入参数.");
ChangedProcessStatus(0);
if (!Validate(out path)) return;

DisplayProcessStatus("正在从数据库中组织数据.");
Cursor.Current = Cursors.Cross;
List<string> msgs = _PaiShuiGongSiWenBenBLL.SelectPaiShuiGongSiWenBen();

if (msgs.Count == 0)
{
DisplayProcessStatus("写入0条记录.");
progressBarControl1.Position = 100;
DisplayProcessStatus("处理完成.");
return;
}

DisplayProcessStatus("正在写入文件.");
int count = msgs.Count;

FileStream fs = new FileStream(path, FileMode.Create);
StreamWriter sw = new StreamWriter(fs);

using (fs)
using (sw)
{
for (int i = 0; i < count; i++)
{
sw.WriteLine(msgs[i]);
System.Threading.Thread.Sleep(200);
ChangedProcessStatus((int)((decimal)(i + 1) / (decimal)count * 100));
Application.DoEvents();
}
}
Cursor.Current = Cursors.Defa