C#判断大批量的路径是否存在时，如何缩短判断时间

[DllImport("Shlwapi.dll", SetLastError = true, CharSet = CharSet.Auto)]        
public extern static bool PathFileExists(string path);        
void Exists()
        {            
        {            // A StringBuilder is required for interops calls that use strings
            StringBuilder builder = new StringBuilder();
            builder.Append(@"C:\test.txt");            bool exists = PathFileExists(builder.ToString());
        }

来源：https://www.cnblogs.com/Jian-Zhang/p/6070435.html