From what baseline configuration?
Check the tips in http://www.oracle.com/technetwork/topics/php/underground-php-oracle-manual-098250.html
If you aren't using persistent connections, use them. If DB host server memory is an issue, use DRCP: http://www.oracle.com/technetwork/topics/php/whatsnew/php-scalability-ha-twp-128842.pdf
Thanks for that post. DRCP looks like it would help unfortunately my DEV environment is on 10g so I can't test at the moment. The production instance is 11g so when I move to that environment I will test and report back the results so others can benefit.