PHP performance issue

CentOS 4.2, Apache 2.0, PHP 4.3.9, PHP loaded as a module

I've got a fairly complicated page using MySQL that from the user's
perspective, takes about 2 seconds to load. According to TOP, the CPU
goes to 100% during this time.

If I use microtime() at the top and the bottom of the code, it says the
code takes 0.3 seconds.

So how can I find out where the slow load times are coming from? I'm
running my tests from another computer on the same switch.

Thanks.

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