Using related posts plugin keeps your readers engaged in your site by letting them know that your site have other things that they may like. With some backend tricks, this plugin can make post suggestions based on what the reader is viewing, page views, and average time on the site. Related posts also let you have the opportunity to add advertisements to your site.
However, there is a drawback when using such plugin. It can destroy the site’s performance or worst, bring it down. It is because of the FULLTEXT index of MySQL.