Fixes #5887 - Knowledge Base search extremely slow despite fast Elasticsearch response

app/assets/javascripts/app/controllers/knowledge_base/search_field_widget.coffee

@@ -58,7 +58,7 @@ class App.KnowledgeBaseSearchFieldWidget extends App.Controller
 
     @delay( =>
       @makeRequest(query)
-    , 100, 'makeRequest')
+    , 500, 'makeRequest')
 
   data: (query) ->
     attrs = {

db/migrate/20190531180304_initialize_knowledge_base.rb

@@ -78,6 +78,11 @@ class InitializeKnowledgeBase < ActiveRecord::Migration[5.0]
       t.references :published_by, foreign_key: { to_table: :users }
 
       t.timestamps limit: 3, null: false
+
+      # Covers published (published+internal) and internal (published+internal+archived) scopes
+      t.index %i[published_at archived_at internal_at], name: 'index_kb_answers_publishing_dates'
+      # Covers archived scope
+      t.index [:archived_at]
     end
 
     create_table :knowledge_base_answer_translation_contents do |t| # rubocop:disable Rails/CreateTableWithTimestamps

db/migrate/20251212150958_kb_add_dates_index.rb

@@ -0,0 +1,17 @@
+# Copyright (C) 2012-2025 Zammad Foundation, https://zammad-foundation.org/
+
+class KbAddDatesIndex < ActiveRecord::Migration[7.0]
+  def change
+    # return if it's a new setup
+    return if !Setting.exists?(name: 'system_init_done')
+
+    change_table :knowledge_base_answers do |t|
+      # Covers published (published+internal) and internal (published+internal+archived) scopes
+      t.index %i[published_at archived_at internal_at], name: 'index_kb_answers_publishing_dates'
+      # Covers archived scope
+      t.index [:archived_at]
+    end
+
+    KnowledgeBase::Answer.reset_column_information
+  end
+end