diff --git a/ChatController/ChatController.csproj b/ChatController/ChatController.csproj
index 89e43ea..21f02f4 100644
--- a/ChatController/ChatController.csproj
+++ b/ChatController/ChatController.csproj
@@ -76,6 +76,7 @@
     <Compile Include="Converter\BoolToVisibilityConverter.cs" />
     <Compile Include="Converter\StringEmptyToVisibilityConverter.cs" />
     <Compile Include="Converter\StringToBoolConverter.cs" />
+    <Compile Include="Core\OwnChatCache.cs" />
     <Compile Include="Data\LookupResult.cs" />
     <Compile Include="Data\OwnChatApi.cs" />
     <Compile Include="Extensions\IDictionaryTExtensions.cs" />
diff --git a/ChatController/ChatKlassen/ChatMessage.cs b/ChatController/ChatKlassen/ChatMessage.cs
index dd0ea6c..a1a6be3 100644
--- a/ChatController/ChatKlassen/ChatMessage.cs
+++ b/ChatController/ChatKlassen/ChatMessage.cs
@@ -3,6 +3,7 @@ using System.ComponentModel;
 using System.Text.RegularExpressions;
 using System.Windows;
 using System.Windows.Media;
+using ChatController.Core;
 using ChatController.Utilities;
 using static System.Windows.HorizontalAlignment;
 
@@ -73,7 +74,16 @@ namespace ChatController.ChatKlassen
 
             FilePath = pUrl;
 
-            Thumbnail = Utils.CreateImageSourceFromPath(pSmallerImagePath);
+            var cache = OwnChatCache.GetInstance();
+
+            var imgSrc = cache.GetImageSourceFromCache($"group-{pGroupId}");
+
+            if(imgSrc == null)
+            {
+                imgSrc = Utils.CreateImageSourceFromPath(pSmallerImagePath);
+            }
+
+            Thumbnail = imgSrc;
             
             GroupId = pGroupId;
 
diff --git a/ChatController/Core/OwnChatCache.cs b/ChatController/Core/OwnChatCache.cs
new file mode 100644
index 0000000..4bd43f1
--- /dev/null
+++ b/ChatController/Core/OwnChatCache.cs
@@ -0,0 +1,133 @@
+using System;
+using System.Collections.Generic;
+using System.Drawing;
+using System.Windows.Media;
+
+namespace ChatController.Core
+{
+    public class OwnChatCache
+    {
+        // Key-> "group-127" oder "user-938"
+        private Dictionary<string, ImageSourceCacheObject> _ImageSources  = new Dictionary<string, ImageSourceCacheObject>();
+
+        // Key-> "group-127" oder "user-938"
+        private Dictionary<string, BitmapCacheObject> _Bitmaps = new Dictionary<string, BitmapCacheObject>();
+
+        private static OwnChatCache _Instance;
+
+        private OwnChatCache() { }
+
+        public static OwnChatCache GetInstance()
+        {
+            return _Instance ?? (_Instance = new OwnChatCache());
+        }
+
+        public void ClearAll()
+        {
+            ClearImageSources();
+            ClearBitmaps();
+        }
+
+        public void ClearImageSources()
+        {
+            _ImageSources.Clear();
+        }
+
+        public void ClearBitmaps()
+        {
+            _Bitmaps.Clear();
+        }
+
+        public ImageSource GetImageSourceFromCache(string key)
+        {
+            if(key == null || _ImageSources == null || !_ImageSources.ContainsKey(key))
+            {
+                return null;
+            }
+
+            var imageSourceCacheObject = _ImageSources[key];
+
+            var expirationDate = imageSourceCacheObject.ExpirationDate;
+
+            return expirationDate < DateTime.Now ? null : imageSourceCacheObject.Image;
+        }
+
+        public void AddImageToCache(string key, ImageSource imageSource)
+        {
+            if(_ImageSources == null)
+            {
+                _ImageSources = new Dictionary<string, ImageSourceCacheObject>();
+            }
+
+            var newImageSourceCacheObject = new ImageSourceCacheObject(imageSource);
+
+            if(_ImageSources.ContainsKey(key))
+            {
+                _ImageSources[key] = newImageSourceCacheObject;
+            }
+            else
+            {
+                _ImageSources.Add(key, newImageSourceCacheObject);
+            }
+        }
+
+        public Bitmap GetBitmapFromCache(string key)
+        {
+            if(key == null || _Bitmaps == null || !_Bitmaps.ContainsKey(key))
+            {
+                return null;
+            }
+
+            var bitmapCacheObject = _Bitmaps[key];
+
+            var expirationDate = bitmapCacheObject.ExpirationDate;
+
+            return expirationDate < DateTime.Now ? null : bitmapCacheObject.Bitmap;
+        }
+
+        public void AddBitmapToCache(string key, Bitmap bitmap)
+        {
+            if(_Bitmaps == null)
+            {
+                _Bitmaps = new Dictionary<string, BitmapCacheObject>();
+            }
+
+            var newBitmapCacheObject = new BitmapCacheObject(bitmap);
+
+            if(_Bitmaps.ContainsKey(key))
+            {
+                _Bitmaps[key] = newBitmapCacheObject;
+            }
+            else
+            {
+                _Bitmaps.Add(key, newBitmapCacheObject);
+            }
+        }
+    }
+
+    public class ImageSourceCacheObject
+    {
+        public DateTime ExpirationDate { get; }
+
+        public ImageSource Image { get; }
+
+        public ImageSourceCacheObject(ImageSource imageSource)
+        {
+            ExpirationDate = DateTime.Now.AddYears(1);
+            Image = imageSource;
+        }
+    }
+
+    public class BitmapCacheObject
+    {
+        public DateTime ExpirationDate { get; }
+
+        public Bitmap Bitmap { get; }
+
+        public BitmapCacheObject(Bitmap bitmap)
+        {
+            ExpirationDate = DateTime.Now.AddYears(1);
+            Bitmap = bitmap;
+        }
+    }
+}
diff --git a/ChatController/HauptKlassen/Chat.cs b/ChatController/HauptKlassen/Chat.cs
index 952bbb4..272e5bb 100644
--- a/ChatController/HauptKlassen/Chat.cs
+++ b/ChatController/HauptKlassen/Chat.cs
@@ -3,20 +3,19 @@ using Newtonsoft.Json;
 
 using System;
 using System.Collections.Generic;
-using System.Diagnostics;
 using System.Drawing;
 using System.Drawing.Imaging;
 using System.IO;
 using System.Linq;
 using System.Net;
 using System.Net.Http;
-using System.Text;
 using System.Threading;
 using System.Windows;
 using System.Windows.Data;
 using System.Windows.Forms;
 using System.Windows.Media;
 using System.Windows.Media.Imaging;
+using ChatController.Core;
 using ChatController.LoginKlassen;
 using ChatController.Utilities;
 using ChatController.Utilities.Extensions;
@@ -79,7 +78,6 @@ namespace ChatController.HauptKlassen
         }
 
         // WebRequest
-        // TODO: Auth-Token zum Header hinzufügen
         private ImageSource DownloadImage(string pUri)
         {
             try
@@ -144,7 +142,6 @@ namespace ChatController.HauptKlassen
 
                     if (!string.IsNullOrEmpty(serverResponse))
                     {
-                        Debug.WriteLine(serverResponse);
                         _UserMessages = JsonConvert.DeserializeObject<UserMessages>(serverResponse);
 
                         if (_UserMessages.Response.HasMorePages)
@@ -905,7 +902,7 @@ namespace ChatController.HauptKlassen
 
                     var imageName = Utils.GenerateTempName() + ".jpg";
 
-                    System.Drawing.Image image = bitmap;
+                    Image image = bitmap;
 
                     AddMediumContextDerNachrichtView(Utils.ImageToByteArray(image), imageName, pGroupOid);
                         
@@ -1147,11 +1144,27 @@ namespace ChatController.HauptKlassen
                     }
                 }
 
-                var avatar = Utils.AvatarToImageSourceConverter(groupInput.Avatar, groupInput.OnlyEmployees, groupInput.Users.Length > 2);
+                var key = $"group-{groupInput.Oid}";
 
-                var profilePicture = Utils.ConvertAvatarToBitmap(groupInput.Avatar, groupInput.OnlyEmployees, groupInput.Users.Length > 2);
+                var cacheInstance = OwnChatCache.GetInstance();
 
-                contacts.Add(new Contact(groupInput.Name, groupInput.LastMessage, formattedTime, groupInput.Oid, userIdManage, groupInput.OnlyEmployees, groupInput.Users.Length, groupInput.CanWrite, groupInput.AccentColor, profilePicture, avatar));
+                var imgSrc = cacheInstance.GetImageSourceFromCache(key);
+
+                if(imgSrc == null)
+                {
+                    imgSrc = Utils.AvatarToImageSourceConverter(groupInput.Avatar, groupInput.OnlyEmployees, groupInput.Users.Length > 2);
+                    cacheInstance.AddImageToCache(key, imgSrc);
+                }
+
+                var bmp = cacheInstance.GetBitmapFromCache(key);
+
+                if(bmp == null)
+                {
+                    bmp = Utils.ConvertAvatarToBitmap(groupInput.Avatar, groupInput.OnlyEmployees, groupInput.Users.Length > 2);
+                    cacheInstance.AddBitmapToCache(key, bmp);
+                }
+
+                contacts.Add(new Contact(groupInput.Name, groupInput.LastMessage, formattedTime, groupInput.Oid, userIdManage, groupInput.OnlyEmployees, groupInput.Users.Length, groupInput.CanWrite, groupInput.AccentColor, bmp, imgSrc));
 
                 if(pShouldUpdateLastTimeStamp)
                 {
diff --git a/ChatController/Utilities/Utils.cs b/ChatController/Utilities/Utils.cs
index 21a8ddc..1874955 100644
--- a/ChatController/Utilities/Utils.cs
+++ b/ChatController/Utilities/Utils.cs
@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.Drawing;
 using System.Drawing.Imaging;
 using System.IO;
@@ -36,6 +37,8 @@ namespace ChatController.Utilities
 
             if(!string.IsNullOrWhiteSpace(linkToPicture))
             {
+                Debug.WriteLine("Lade Bitmap herunter...");
+
                 var client = new RestClient(linkToPicture);
 
                 var request = new RestRequest(Method.GET)
@@ -132,6 +135,8 @@ namespace ChatController.Utilities
         {
             if (!string.IsNullOrEmpty(pPathToImageFile))
             {
+                Debug.WriteLine("Lade Bild herunter...");
+
                 Bitmap bitmap = null;
 
                 var client = new RestClient(pPathToImageFile);