Hey there! We're going to need some more details on this before we can provide advice. When you say "site analysis" are you using a site monitoring tool or scanner that told you this information? If so, are you able to replicate this when visiting your site? And if that is also the case, do you see anything in either the local error log or the Apache log (/etc/apache2/logs/error_log) that may give a clue about this behavior?
I believe that would be up to the code of the site. Some sites load all images at once, and some only load as you scroll the page, but I don't believe there is going to be anything on the cPanel side of things that will change that behavior. Is this a custom site that was created for you? If so, reaching out to the site designer is likely the best way to get that handled.