I'm developing websites in a Windows 7 machine.
When I've installed Firefox I've found some performance issue specially on connecting to the localhost, googling around I've discovered that it's related to the use of IPv6 by the browser to resolve urls.
about: config and setting
network.dns.disableIPv6 to true the problem is gone.
Now I've the same issue with Google Chrome, but I can't find a way (if there's a way) to do the same I've done with Firefox.