diff --git a/boards/views/__init__.py b/boards/views/__init__.py
--- a/boards/views/__init__.py
+++ b/boards/views/__init__.py
@@ -1,3 +1,8 @@
+from datetime import datetime, timedelta
+from django.db.models import Count
+
+OLD_USER_AGE_DAYS = 90
+
 __author__ = 'neko259'
 
 import hashlib
@@ -521,6 +526,8 @@ def _get_user(request):
         user = User.objects.create(user_id=new_id, rank=RANK_USER,
                                    registration_time=time_now)
 
+        _delete_old_users()
+
         session['user_id'] = user.id
     else:
         user = User.objects.get(id=session['user_id'])
@@ -588,3 +595,17 @@ def _get_template_thread(thread_to_show)
         'last_replies': last_replies,
         'skipped_replies': skipped_replies_count,
         }
+
+
+def _delete_old_users():
+    """
+    Delete users with no favorite tags and posted messages. These can be spam
+    bots or just old user accounts
+    """
+
+    old_registration_date = datetime.now().date() - timedelta(OLD_USER_AGE_DAYS)
+
+    for user in User.objects.annotate(tags_count=Count('fav_tags')).filter(
+            tags_count=0).filter(registration_time__lt=old_registration_date):
+        if not Post.objects.filter(user=user).exists():
+            user.delete()
diff --git a/changelog.markdown b/changelog.markdown
--- a/changelog.markdown
+++ b/changelog.markdown
@@ -7,4 +7,5 @@ thread.
 * Added new gallery with search links and image metadata
 
 # 1.6 Amon #
-* Deleted threads are moved to archive instead of permanent delete
\ No newline at end of file
+* Deleted threads are moved to archive instead of permanent delete
+* User management fixes and optimizations
\ No newline at end of file