title: NLog cpu performance issue
body: <p>I have problem with this method in NLog library: <code>NLog.Targets.Wrappers.AsyncTargetWrapper.ProcessPendingEvents(object state)</code></p>
  
  <p>It consume too much cpu time. I have long running windows service using Nlog and after two days my service consume over 80% cpu time (one core is almost on 80%, second 30%). It is not 100% cpu time but it is changing and after cca 2 hours its back to normal. So I have run profiler and this metod maybe cause it: NLog.Targets.Wrappers.AsyncTargetWrapper.ProcessPendingEvents(object state)</p>
  
  <p>I have 10 file targets all are setted as async. It is a fact that I have lot of logging in my app but only on level Trace, if I switched to Info level it not helped.</p>
  
  <p>Can you help me, should I decrease logging in my app?</p>