diff --git a/li.strolch.agent/src/main/java/li/strolch/agent/api/ObserverEvent.java b/li.strolch.agent/src/main/java/li/strolch/agent/api/ObserverEvent.java
index 41cdbbe8b..648a6e6bd 100644
--- a/li.strolch.agent/src/main/java/li/strolch/agent/api/ObserverEvent.java
+++ b/li.strolch.agent/src/main/java/li/strolch/agent/api/ObserverEvent.java
@@ -1,5 +1,12 @@
 package li.strolch.agent.api;
 
+import static java.util.stream.Collectors.groupingBy;
+import static java.util.stream.Collectors.joining;
+
+import java.util.List;
+import java.util.Map;
+
+import li.strolch.model.StrolchElement;
 import li.strolch.model.StrolchRootElement;
 import li.strolch.utils.collections.MapOfLists;
 
@@ -7,4 +14,29 @@ public class ObserverEvent {
 	public MapOfLists<String, StrolchRootElement> added = new MapOfLists<>();
 	public MapOfLists<String, StrolchRootElement> updated = new MapOfLists<>();
 	public MapOfLists<String, StrolchRootElement> removed = new MapOfLists<>();
+
+	@Override
+	public String toString() {
+		String added = this.added.isEmpty() ? "0" : collectSizes(this.added);
+		String updated = this.updated.isEmpty() ? "0" : collectSizes(this.updated);
+		String removed = this.removed.isEmpty() ? "0" : collectSizes(this.removed);
+		return "ObserverEvent{added=" + added + ", updated=" + updated + ", removed=" + removed + "}";
+	}
+
+	private String collectSizes(MapOfLists<String, StrolchRootElement> added) {
+		return added.stream()
+				.map(entry -> entry.getKey() + "=[" + collectSizeByType(entry) + "]")
+				.collect(joining(","));
+	}
+
+	private static String collectSizeByType(Map.Entry<String, List<StrolchRootElement>> entry) {
+		String sizeByType = entry.getValue()
+				.stream()
+				.collect(groupingBy(StrolchElement::getType))
+				.entrySet()
+				.stream()
+				.map(e -> e.getKey() + "=" + e.getValue().size())
+				.collect(joining(","));
+		return sizeByType;
+	}
 }
diff --git a/li.strolch.agent/src/main/java/li/strolch/agent/impl/DefaultObserverHandler.java b/li.strolch.agent/src/main/java/li/strolch/agent/impl/DefaultObserverHandler.java
index 81baebbd9..e7e294051 100644
--- a/li.strolch.agent/src/main/java/li/strolch/agent/impl/DefaultObserverHandler.java
+++ b/li.strolch.agent/src/main/java/li/strolch/agent/impl/DefaultObserverHandler.java
@@ -18,6 +18,7 @@ package li.strolch.agent.impl;
 import static li.strolch.model.Tags.AGENT;
 import static li.strolch.runtime.StrolchConstants.SYSTEM_USER_AGENT;
 import static li.strolch.utils.collections.SynchronizedCollections.synchronizedMapOfLists;
+import static li.strolch.utils.helper.StringHelper.formatNanoDuration;
 
 import java.text.MessageFormat;
 import java.util.ArrayList;
@@ -87,6 +88,8 @@ public class DefaultObserverHandler implements ObserverHandler {
 			try {
 				ObserverEvent event = this.eventQueue.takeFirst();
 
+				long start = System.nanoTime();
+
 				for (String key : event.added.keySet()) {
 					List<StrolchRootElement> list = event.added.getList(key);
 					if (list != null)
@@ -103,6 +106,10 @@ public class DefaultObserverHandler implements ObserverHandler {
 						notifyRemove(key, list);
 				}
 
+				long durationNanos = System.nanoTime() - start;
+				if (durationNanos >= 250000000L)
+					logger.warn("Observer update for event " + event + " took " + formatNanoDuration(durationNanos));
+
 			} catch (InterruptedException e) {
 				if (this.run)
 					logger.error("Failed to do updates!", e);