diff --git a/Build/MQTTnet.nuspec b/Build/MQTTnet.nuspec
index 52acf561..34e563bc 100644
--- a/Build/MQTTnet.nuspec
+++ b/Build/MQTTnet.nuspec
@@ -15,6 +15,7 @@
 * [Client] The ManagedClient options now allow configuring the interval for connection checks.
 * [Server] Added the Endpoint of the Adapter (remote IP and port) to the connection validation callback.
 * [Server] The ipv4 and ipv6 endpoint can be disabled now by setting the bound IP address to _None_.
+* [Server] Fix a bug in the keep alive monitor which caused high CPU load (thanks to @GarageGadget).
     </releaseNotes>
     <copyright>Copyright Christian Kratky 2016-2018</copyright>
     <tags>MQTT Message Queue Telemetry Transport MQTTClient MQTTServer Server MQTTBroker Broker NETStandard IoT InternetOfThings Messaging Hardware Arduino Sensor Actuator M2M ESP Smart Home Cities Automation Xamarin</tags> 
diff --git a/Source/MQTTnet/Server/MqttClientKeepAliveMonitor.cs b/Source/MQTTnet/Server/MqttClientKeepAliveMonitor.cs
index b3628612..8afb7acd 100644
--- a/Source/MQTTnet/Server/MqttClientKeepAliveMonitor.cs
+++ b/Source/MQTTnet/Server/MqttClientKeepAliveMonitor.cs
@@ -70,7 +70,9 @@ namespace MQTTnet.Server
                 while (!cancellationToken.IsCancellationRequested)
                 {
                     // Values described here: [MQTT-3.1.2-24].
-                    if (!_isPaused && _lastPacketReceivedTracker.Elapsed.TotalSeconds > keepAlivePeriod * 1.5D)
+                    // If the client sends 5 sec. the server will allow up to 7.5 seconds.
+                    // If the client sends 1 sec. the server will allow up to 1.5 seconds.
+                    if (!_isPaused && _lastPacketReceivedTracker.Elapsed.TotalSeconds >= keepAlivePeriod * 1.5D)
                     {
                         _logger.Warning(null, "Client '{0}': Did not receive any packet or keep alive signal.", _clientSession.ClientId);
                         _clientSession.Stop(MqttClientDisconnectType.NotClean);
@@ -78,7 +80,11 @@ namespace MQTTnet.Server
                         return;
                     }
 
-                    await Task.Delay(keepAlivePeriod, cancellationToken).ConfigureAwait(false);
+                    // The server checks the keep alive timeout every 50 % of the overall keep alive timeout
+                    // because the server allows 1.5 times the keep alive value. This means that a value of 5 allows
+                    // up to 7.5 seconds. With an interval of 2.5 (5 / 2) the 7.5 is also affected. Waiting the whole
+                    // keep alive time will hit at 10 instead of 7.5 (but only one time instead of two times).
+                    await Task.Delay(TimeSpan.FromSeconds(keepAlivePeriod * 0.5D), cancellationToken).ConfigureAwait(false);
                 }
             }
             catch (OperationCanceledException)