NLog cpu performance issue

According to this thread I would also guess that setting a higher number for timeToSleepBetweenBatches should reduce the high cpu time. Seems that the 2.0 beta of NLog should fix this behavor by only having one lazy writer thread running at a time.

In the meanwhile you don't have to change the source code to change timeToSleepBetweenBatches. You can set it in the configuration file:

<targets>
  <target xsi:type="AsyncWrapper"
          name="String"
          queueLimit="Integer"
          timeToSleepBetweenBatches="Integer"
          batchSize="Integer"
          overflowAction="Enum">
    <target xsi:type="wrappedTargetType" ...target properties... />
  </target>
</targets>

Buffering Options
timeToSleepBetweenBatches - Time in milliseconds to sleep between batches.Integer Default: 50

I took a brief look into the sources. My guess:

try to change ctor AsyncTargetWrapper(wrappedTarget, queueLimit, overflowAction) ...

this.TimeToSleepBetweenBatches = 50;

to something less frequent:

this.TimeToSleepBetweenBatches = 1000;

so the internal timer will not fire every 50ms !