How to to decrease the resource usage

Hi,
Yesterday I got my Semi-dedicated (SDX) server blocked my zenphoto scripts.
The reason why was (according to them) ...
running various CPU intensive php scripts which are causing very high load on the server and due to which server is going under very high load. Please have a look at the follow details about your php scripts running in parallel.
%CPU 104 - /opt/cpanel/ea-php56/root/usr/bin/php-cgi /home/xxxxxxx/public_html/gallery/index.php
After many discussion, they told me ... to check and optimize the code to decrease the resource usage
I never experienced that kind of problem before.
Is there a way to do that in the zenphoto script ?
I am running the latest version of the script.
It was probably a one shot event that triggered the server to block the php script, but they were not smart enough to unblock it later on to see if the problem is gone!
Thanks for your input