I am wondering what php modules you guys find most useful or nneeded with these CMS systems or just in general for a Debian 8.3 / ISPConfig 3.1BETA installation?
Did that, but wanted to know if there were any others, that could help out with functionality and speed.
Installing PHP modules that are not required by a cms will just make PHP bloated and will slow it down, so I won't recommend to install modules that the cms systems on your server don't need. If you like to make the php processing faster, then install PHP 7 as additional PHP version: https://www.howtoforge.com/tutorial/install-php-7-on-debian-8-jessie/
I would suggest using fail2ban and adding specific Wordpress and other CMS login pages to prevent hackers wasting resources. This is a good place to checkout: http://moiseevigor.github.io/softwa...-of-service-wordpress-joomla-drupal-fail2ban/ Also google 'fail2ban persistent' for suggestions on how to have your banned IP block lists survive reboots and restarts.
webguyz: Nice, but already using fail2ban, maldetect and other security measures What I was looking for, were options to add functionality on the server for some plugins, using PHP.
Felan, you can also add caches like redis and memcached for increasing your site speed too. Hosting which I am using i.e. Cloudways have provided me these caches along with varnish and Nginx when I have run my server for the first time. When I deployed my site to there it increases my site load time a lot.