We’ve just upgraded two PCs to Windows 7. Everything went well and there’s no issues with drivers or speed in general until we install WAMP on one of them.

After installing WAMP the PC was still running at normal speed with WAMP running but whenever we tried to access a simple website we had set up there was a 4 or 5 second lag before the page was displayed.

We were using a simple html file to test it with so that ruled out there being a problem with PHP or MySQL in WAMP so it was just Apache that were were finding slow to access – either locally or through the other Windows 7 PC.

I thought it may be Windows firewall and when I shut the firewall down then requests to Apache speeded up to normal speed. Obviously running with the firewall down isn’t ideal so I thought it might be related to a problem I had using localhost on Vista.

Eventually I found disabling IPv6 on the WAMP PC’s network adapter fixed the problems. We don’t need to run IPv6 and running both IPv4 and IPv6 along with Windows firewall and Apache must cause a bottleneck somewhere.