Zend optimizer is a plugin to php which allows a server to read zend encoded files as well as serve as a platform to install zend modules such as eaccelerator. The installation is incredibly simple thanks to zend's script. The current 10a version works with php 4.4.1 as well as the latest version of eaccelerator. Currently the cPanel scripts do NOT install a version of zend compatible with php 4.4.1 so a manual install must be done.
I have a local copy of the files:
cd /usr/local/src
wget
http://www.eth0.us/files/ZendOptimiz...21-i386.tar.gz
tar -zxf ZendOptimizer-2.5.10a-linux-glibc21-i386.tar.gz
cd ZendOptimizer-2.5.10a-linux-glibc21-i386
./install
Now just hit enter a few times until it is done and you are done! It is as easy as that.
Check for a more recent version at
http://www.zend.com/products/zend_optimizer
Another tutorial
http://www.webhostgear.com/184.html
If all else ask your host of the VPS to install it for you.