AJAX - How can I build a notification system, that is constantly getting updated, without slowing down my website too much?

Question

I am a beginner to web development, and I am trying to do a notification system with AJAX and jQuery.

In my web application, I have a comment system where you can mention another user. After a comment mentioning a certain user has been written, a new entry on my notifications table will be added, containing the comment, the id of the user who commented and the id of the user(s) who will receive the comment. After the notification is stored in the database, I want the person that was mentioned to receive the notification.

To that effect, I decided to use AJAX. Using the setTimeout() method, I am sending an AJAX request to the database every 2 seconds, and with that, I can display the notifications visually to the user that is meant to receive them.

My only concern is that this will slow down the site once I connect it with a server.

So, I was looking for a way that would allow me to implement a notifications system without slowing the site too much, since the one that I am using currently doesn't seem very efficient.

I would appreciate any help.