cPanel Version 94.0 (build 25)
Apache Version 2.4.54
PHP Version 5.6.40
MySQL Version 5.7.23-23
The webserver Apache 2.4.54 is the current up to date version. I can't say anything about cPanel. The Wikipedia article says, the up to date version is 98 (stand 2022-08-10). The MySQL package is more or less outdated, but the version gets security updates until October 2023.
But one thing is inexcusable. How one can provide PHP in version 5.6 in the year 2022? PHP 5.6 doesn't got security fixes after December 2018. That's more or less three and a half year ago. Even PHP 7.4, the last major version in the PHP-7-branch reaches end of life in November 2022.
I didn't take much notice of the versions before the migration as everything was loading quick and we were happy.
Pages with just text and images under 500KB seem to load quick but any image over that takes a while. Gifs that took maybe 3 seconds to load before migration now take over 1 minute, you literally see every frame of the gif load.
Would the nameservers have anything to do with it? I noticed they haven't changed.
I can't imagine that. The nameserver does nothing else than to translate the domain name in a request into the matching IP(s) (name resolution). If your lightweight pages loads quickly but pages with large images or a lot of data loads extremly slow, the name resolution has presumably nothing to do with it.
Trenne niemals Müll, denn er hat nur eine Silbe!