PHP execution speed in Win2K

I have my dev machine on Win2003 Server and my production on Win2K Server. Does anyone know of a setting on the win2K env which would cause it to perform very slowly? After letting the app ly dormant for only a few minutes and then requesting a new page, the app is very slow to respond, then it's fine for the next few pages, then if you stop for a minute or so and request another page, you get the same sluggish response. This does not occur on win2003 server. Is there a setting I have missed perhaps? thanks Alan