Automatically inserted HTML comments

I’ve noticed using when using WordPress to edit documents that it automatically adds html comments like

<!– wp:paragraph –>

.

I am not sure what the purpose of these are, but is there a possiblity that having this text in each page will slow down the render speed of the page in web browsers.

I remember some idea about avoiding blank spaces in documents because even these will slow down the download speed of a file.

Is there any way of stopping the automatic insertion of these comments?