Php – Windows Server 2008 R2 running PHP poor performance

At work we have a Windows Server 2008 R2 setup as webserver.
We have IIS installed and with the Web Platform Installer we have installed PHP.

The problem now is, the performance of the server is quite poor. The app runs totally fine on a lot of different machines (I've tried on Windows 7, OSX, Linux Ubuntu and even another 2008 R2 server).
The page is loading, but it takes about 2-3 seconds, where all the other machines are ready in about 200-400 milliseconds.
I've tried to debug what is happening and it looks like the server is just 'waiting' for 2 seconds on every request.
I looked at the timelines from Firebug and Chrome, and they show me that they're sending the request in a few milliseconds, then they're waiting for 2 seconds, before the server will send back a response.

What could cause these 2 seconds?
Normally I would say "a slow running app" but given the fact that I tried it out on a lot of other machines, and the app is running fine, I don't think that's the problem.

So I hope someone can help me, or at least give me a push in the right direction.

EDIT:
I have been able to shave about half of the 'delay' time off, by setting all the database hosts to 127.0.0.1 instead of localhost. Don't know why, but it does seem to speed things up. Got to love Microsoft Servers….

EDIT2:
I have uploaded my ini file over here, please have a look if you can find anything
https://gist.github.com/Crinsane/6577840

Thanks in advance!