find each user

plugin.rb

@@ -873,8 +873,7 @@ module ::DiscourseAssign
   end
 
   on(:group_destroyed) do |group, user_ids|
-    user_ids.each do |user_id|
-      user = User.find(user_id)
+    User.where(id: user_ids).find_each do |user|
       user.notifications.for_assignment(group.assignments.select(:id)).destroy_all if user
     end