Why there is anomalous performance of php with apache httpd??

>
> I have windows XP sp3 .Now, I am
> using recent builds of Apache
> HTTPD 2.2.22 and PHP 5.3.10.
> I am using this tutorial
>
>    http://webdevcodex.com/**tutorial-installing-apache2-**
php5-mysql5-phpmyadmin3-**windows-7-vista/<http://webdevcodex.com/tutorial-installing-apache2-php5-mysql5-phpmyadmin3-windows-7-vista/>

> But whenever after installing SP3 there
> will either PHP compilation sometimes
> fast or sometimes slower.Otherwise
> server gets crashed.I really get screwed.
> Can you help in setting Apache and php as
> complete setup I have been searching from
> 1and 1/2 year but still not getting definite.
> Thanks for your support.