Performance using Zend and PACE applications

[plancor@xxxxxxxxxxxxxxx]

We have Zend, MySQL and Drupal installed and running on our V5R4 520.  Our 
new web admin is a Drupal advocate and wants to start using Drupal to 
manage some inhouse project sites.  However, performance is really bad. At 
best, 4 second response - at worst 15+ second response.  We have 16GB of 
memory, 78% disk utilization, and normally < 30% CPU Usage.   I found a 
document on Zend's site 
(http://www.zend.com/en/support/knowledgebase.php?kbid=286&view_only=1) 
that offers some suggestions to improve performance.  Since some of these 
recommendations involve changing system values or TCP attributes, I am 
reluctant to change them without knowing beforehand that I will see an 
improvement.  Has anyone made any of these changes and realized an 
improvement in performance?  Has anyone made any other changes that 
resulted in improved performance? 

Any advice regarding improving performance of applications running in PACE 
would be appreciated.