Fix the slow Firefox when using localhost with Visual Studio

Dan Wahlin found out why the Firefox is responding so slow when it tries to connect to the localhost which for example is being used by the Visual Studio 2005 and Visual Studio 2008 integrated webserver. He writes:

It turns out that the slowness is caused by an IPv6 issue with DNS and can easily be resolved by turning IPv6 support off in Firefox while doing localhost testing. To make the change, type about:config in the address bar, locate the network.dns.disableIPv6 setting and double-click on it to set it to true. This does the trick for the Firefox localhost issue on Vista and everything is running fast again.

Good job, thanks Dan!
Source: Fixing Firefox Slowness with localhost on Vista.


#1 Ryan on 01.28.08 at 4:13 am

Awesome. Back to full speed again!! Thats was really starting to piss me off as well.

#2 Brian Chavez on 02.06.08 at 6:33 am

Thanks, this was really starting to make me mad too. At first, I thought it was integrated webserver treating Firefox differently than IE. Glad to know it wasn’t the case!

#3 JEllis on 03.04.08 at 5:03 pm

Didn’t work on XP. Still slow.

#4 Marc on 03.05.08 at 11:12 am

Great tip!

#5 Joshua on 04.17.08 at 10:49 am


#6 Jonathon on 08.17.08 at 10:44 pm

Thanks, very helpful.

#7 toby on 10.22.08 at 2:47 pm

a better way to fix this is to remove the ipv6 address from your hosts file



:: localhost

#8 Johan on 01.14.09 at 9:53 am

Or add localhost to network.dns.ipv4OnlyDomains

#9 Joseph on 12.09.10 at 1:03 pm

youre my hero, awesome! 🙂

Leave a Comment