I installed XAMPP on my Windows 2003 SBS server a few months back. It worked really smoothly for some time but lately there have been response time issues.
At some point the server started to serve pages really slow also in the local LAN. It doesn't matter if you use the DNS-name or the IP, retrieving pages takes even up to 10 seconds. ("waiting for 10.0.0.1.." is displayed for a long time but then the page itself opens fast).
The same things happens when I try to open 127.0.0.1 using the server's own browser locally.
I tried pinging the server from another computer in the same LAN. The replies come in less than 0.2ms, so the problem is not on the physical layer. I guess it's either Apache or the Server 2003 itself.
I even uninstalled IIS just to make sure but it didn't make any difference. MySQL shouldn't be the bottleneck either. Also static pages are opened as slowly as dynamic pages.