javascript – Dimensioning problem for the event sent by the server with simultaneous users of more than 10 KB

I expect that the HSE user will receive a last minute notification on my site information. It is built on WordPress with PHP 7.0. I've found that, compared to ajax pooling, SSE is a very good option for displaying the latest news as soon as the database is updated without reloading the browser.

I've used the following code to test the technology:

            var source = new EventSource ("breaknews.php");
//breakingnews.php imports DB break notes.
source.onmessage = function (event)
{
var p = document.createElement ("p");
var t = document.createTextNode (event.data);
p.appendChild (t);
document.getElementById ("breakNews"). appendChild (p);
};

The code presented above worked perfectly for me on my development server. But my only concern is how this method will work for the site with around 10,000 simultaneous users.

Thank you all for your valuable ideas.