Select specific fields from query
I tried eager loading before, and I couldn't figure out how to do it. 

https://docs.craftcms.com/v3/dev/eager-loading-elements.html

Now I just query it using SQL. I know it's a bit hacking, but it gets the job done. The DB structure of craft_content table hasn't change since Craft 2 (when I started using craft), so its unlikely that future updates will break your code.

$command = Craft::$app-&gt;getDB()-&gt;createCommand("SELECT `ct`.`id`, `cc`.`title` FROM `craft_tags` as `ct` left join `craft_content` as `cc` on `ct`.`id` = `cc`.`elementId`");
$tags = $command-&gt;queryAll();


This is only a quick fix, if anyone had a better idea, just ignore this answer.