I dont see what IPv6 has to do with any of this since they (4 and 6) are completely and totally seperate protocol stacks on the first gen windows implementation.
Nextgen windows TCPIP prefers v6 and framing and the transport layers are shared but 6 will only ever be used if an ipv6 address is used or passed from an application
Slow web browsing may be down to pisscalis traffic shaping or poor transparent web caching server management
You cant really remove IPv6 from Vista. You can only disable it half assedly in the registry and by unticking it in connection properties. You can uninstall from XP no bother though
IPv6 isnt causing the issue here at all, its usually caused by shoddy setup (Not yours!) and programming - eg if you have an IPv6 route to the internet that is not up, as that will be tried first and then timeout. Buggy web browsers like mozilla displayed this behaviour a few versions ago - I dont know if they have fixed this yet? And the sites involved need to have an IPv6 address for this to even become a problem (Which would make sense as you would have people complaining that xyz is fast whilst abc is slow)
If you run sh*tty linux or awesome BSD you can check for ipv6 routes with a ip -6 route.
For some reason in conjunction with ICS having v6 enabled seems to have a problem on some vista machines pre-SP1 but only after a certain amount of time - it isnt even a regular amount of time that you could attribute to something like re-arping happening, its total random times like 15 hours and incredibly annoying.
