There's an issue with FireFox when used to debug ASP.NET applications together with the ASP.NET Development Server on Windows Vista/Windows 7. Performance seems sluggish, especially compared to Internet Explorer. The solution is pretty simple, once you know what the problem is.

The problem is related to an issue with FireFox on these new operating systems to resolve the IPv6 address of localhost. This results in such slow perceived performance, while Internet Explorer doesn't suffer the same fate. To solve the problem, there's two solutions:

The first solution is to disable IPv6 in FireFox alltogether. If you feel this is a bit drastic (as I do) then you can read on to the next solution. Follow these steps:

1. Type in about:config in the address bar of your browser. Heed the warning about the dragons, then proceed to the list of settings.
2. Search or scroll to the setting named network.dns.disableIPv6.
3. Double-click the value to set it to true.
4. Restart your browser.

The second solution is very similar, but instead of disabling all of IPv6 you simply add "localhost" as a domain to the list of domains to ignore IPv6 on, like so:

1. Type in about:config in the address bar of your browser. Skip the warning, then proceed to the list of settings.
2. Search or scroll to the setting named network.dns.ipv4OnlyDomains.
3. Double-click the value to edit it, and add localhost.
4. Restart your browser.

That should make browsing much faster. The original article can be found here.