If you're using Drupal 7, there is a lot simple approach now : http://drupal.org/project/XHProf
XHProf is a hierarchical profiler for PHP. It reports function-level call counts and inclusive and exclusive metrics such as wall (elapsed) time, CPU time and memory usage. A function's profile can be broken down by callers or callees. The raw data collection component is implemented in C as a PHP Zend extension called xhprof. XHProf has a simple HTML based user interface (written in PHP). The browser based UI for viewing profiler results makes it easy to view results or to share results with peers. A callgraph image view is also supported.
Here's how to add the very useful XHPROF - profiler to your DEVELOPMENT instance of your Drupal site
1. Install the XHPROF on your dev instance in php by downloading it.
And installing it manually...
2. Add to the .htaccess file at the bottom =>
3. Add these files to where you want on your test setup, and so that it mirrors the above two lines from your .htaccess file =>
*** please note : http://192.168.0.1/xhprof/xhprof_html/index.php - is relative to where you have put your xhprof folders.
4. Add the following to your php.ini =>
And now at the bottom of your pages you should have "Profiler output" at the bottom of your pages - click to see the data.