feat: preload messages_count

app/services/conversations/filter_service.rb

@@ -60,6 +60,12 @@ class Conversations::FilterService < FilterService
     @conversations = @conversations.includes(
       :taggings, :inbox, { assignee: { avatar_attachment: [:blob] } }, { contact: { avatar_attachment: [:blob] } }, :team
     )
+
+    @conversations = @conversations
+                     .left_joins(:messages)
+                     .select('conversations.*, COUNT(DISTINCT messages.id) AS message_count')
+                     .group('conversations.id')
+
     @conversations.latest.page(current_page)
   end
 end

app/views/api/v1/conversations/partials/_conversation.json.jbuilder

@@ -17,7 +17,7 @@ json.meta do
 end
 
 json.id conversation.display_id
-if conversation.messages.count.zero?
+if conversation.message_count.zero?
   json.messages []
 elsif conversation.unread_incoming_messages.count.zero?
   json.messages [conversation.messages.includes([{ attachments: [{ file_attachment: [:blob] }] }]).last.try(:push_event_data)]