Optimization/Benchmarking tools?

Hello all, I have a couple of web sites which rely heavily on PHP and PostgreSQL. Sometimes, pages which have a lot of dynamic content take several seconds to load. In order to improve my sites' performance, I need to know where the bottlenecks are. I need a tool or tools that would allow me to analyze my sites' behavior to determine where my optimization efforts should be focused: should it be on the PHP scripts, on the SQL queries or database configuration, on aspects of the server configuration, etc. I am using PostgreSQL 8.2.5, PHP 5.2.5, and Microsoft Internet Information Server (IIS) 6.0. I have the Postgres server set up to record any queries whose execution takes longer than a certain interval. By inspecting the logs, I was able to identify poorly performing queries; in most cases, creation of appropriate table indexes resolved the problem. So, that is one aspect of server optimization that I think I have already done pretty well. Other than that, however, I don't really know where improvements need to be made. Thanks to any who can advise. -- Thank you, Lewis Kapell Computer Operations Seton Home Study School