NLog performance

What should the expected overhead be for logging? I have tried this example

 private class Person
 {
    private static Logger logger = LogManager.GetCurrentClassLogger();
    public string Name { get; private set; }
    public Person(string name)
       {
           Name = name;
           logger.Info("New person created with name {0}", name);
       }
  }

  List<Person> people = new List<Person>();
  for (int i = 0; i < MAXTEST; i++)
  {
      people.Add(new Person(i.ToString()));
  }

With MAXTEST values of 100,500,1000, 5000

Results in MAXTEST,noLogging, Logging

100,  25ms, 186ms    
500,  33ms, 812ms    
1000, 33ms, 1554ms
5000, 33ms, 7654ms

Granted one would probably never log this excessive amount, but it this the performance hit one would expect?

I have also tried using the asyncwrapper in the config

 <target name="asyncFile" xsi:type="AsyncWrapper">
   <target name="file" xsi:type="File" fileName="${basedir}/log.txt" />
 </target>