diff --git a/src/Controllers/SettingsController.cs b/src/Controllers/SettingsController.cs
index 2bf2d9b..74b67b4 100644
--- a/src/Controllers/SettingsController.cs
+++ b/src/Controllers/SettingsController.cs
@@ -56,7 +56,13 @@ public class SettingsController : Controller
                 ErrorMessage = "adminUpdateRequestModel is null"
             };
         }
+        AdminSettingsModel currentSettingsModel = await _ldap.GetAdminSettingsModelAsync();
         await _ldap.SetAdminSettingsModelAsync(adminSettingsRequestModel.AdminSettingsModel);
+        if (adminSettingsRequestModel.AdminSettingsModel.UserImagePreloadType != currentSettingsModel.UserImagePreloadType)
+        {
+            IEnumerable<UserModel> users = await _ldap.ListUsersAsync();
+            Task _ = ImageHelper.PreloadUsers(users, adminSettingsRequestModel.AdminSettingsModel.UserImagePreloadType);
+        }
         return new() {
             Success = true
         };
diff --git a/src/Helpers/ImageHelper.cs b/src/Helpers/ImageHelper.cs
index 9124e81..02b6000 100644
--- a/src/Helpers/ImageHelper.cs
+++ b/src/Helpers/ImageHelper.cs
@@ -10,6 +10,7 @@ public static class ImageHelper
     public static Dictionary<int, Dictionary<string, byte[]>> ImageCache = [];
     public static byte[] ResizeAndConvertToWebp(string imageString, int size = 32)
     {
+        if (imageString.Length == 0) return [];
         if (ImageCache.TryGetValue(size, out Dictionary<string, byte[]>? sizeCache)
         && sizeCache.TryGetValue(imageString, out byte[]? result) && result.Length > 0)
         {
@@ -49,6 +50,7 @@ public static class ImageHelper
             {
                 ResizeAndConvertToWebp(user.JpegPhoto, 256);
             }
+            Thread.Sleep(10);
         }
     }
 }
\ No newline at end of file