I recently upgraded to MacOS X Lion. Shortly after that Firefox automatically updated to v6. I began to experience slow DNS lookups.
When you enter a URL into your web browser or click a link to a web page, the first thing it does is ask your DNS servers where that URL points to. Specifically it is looking for the domain name (domainname.com, .net, .org, etc). The DNS server then responds with an IP address which points your browser to it’s target destination which allows the downloading to begin.
For the sake of speed optimization, many websites today use more than one web server to deliver their images and various other files on their pages. One web page may have 3 or more different domains to resolve. If each DNS look up takes 2 seconds, you are looking at 6 seconds of lookup time! Say nothing about the download time. This is why it’s a good to use a service like OpenDNS or Google Public DNS. Often, doing so will noticeably speed up web browsing.
In my particular situation Firefox was trying to take advantage of IPv6 before trying IPv4 which is good and bad. Good for the future of the internet but bad for today’s internet because IPv6 is not in use everywhere yet.
PROBLEM:
- Firefox 6 slow DNS lookups due to priorization of IPv6 over IPv4
THE FIX:
- Enter “about:config” into the URL bar
- Click “I’ll be careful, I promise”
- Enter “DNS” in the filter (just below the URL)
- Double-click on “network.dns.disableIPv6” in the list, setting the value to “True”
- Close and restart Firefox
This dramatically increased the speed of my web browsing. I tested this by enabling and disabling the setting several times just to make sure it wasn’t a network hiccup or somehow related to OpenDNS since I use them.
Thanks for this fix I tried different dns servers with no change. This also helps in firefox 7.
Yah, I made the change in FF 6 and then auto-updated to 7. I checked the setting and it kept.
Thanks for this tip. I just upgraded to OS X Lion last night and my Firefox 7 was taking too long to load web sites. It’s working much faster and better.
Thank you so much! Works much better now even for FF 7
I have noticed that Google seems to be on and off periodically and I think it is somehow related to this setting change. Yesterday safari would pull up google sites while Firefox would not. I changed the setting back and then Firefox could pull it up. It was able to pull up Yahoo and MSN just fine. I wonder if google is doing some IPv6 trickery behind the scenes. It wouldn’t surprise me at all since I know one of their goals is to speed up the web via their DNS project.
Just upgraded to Firefox 8. DNS lookups are still ridiculously slow. Fast in Safari though.
I upgraded to Lion just a couple of days ago. I started noticing the speed almost immediately, especially Google mail. This fix of yours is like night and day. Thank you so much! BTW, running FF 9.0.1
If I do this, does it void the warranty?
I didn’t know Firefox had a warranty. Heh heh. This simply changes a true/false setting in a configuration file. You can change it back just as easily if it doesn’t help. No harm done. Just be sure to quit and restart Firefox after making changes.
Thanks for the lead.. but, this change has had no noticable effect on FF 9’s lookup time for me… right now lookups take about 6 seconds each….yet a ‘host servername’ in the commandline has no noticable delay… something else going on here.
I think it’s time for someone to look at the code to see what is happening….
Jon, are you using OpenDNS, Google Public DNS or any other DNS solution that might require IPv6? If so, consider switching back to your default ISP DNS (set it to auto on your router/modem). Let us know if you find a working solution ok?
no change on my macbook (4gb 2ghz build 2008) with FF 12.0) still slow after changing dns settings to true.
Thanks for this – worked immediately
Great solution!!! Now my lovely mac works faster again.
Perfect!! It worked immediately!
Thanks!!
Worked! Fantastic. Do you have the same fix for Chrome?
I haven’t experienced this issue with Chrome but you can do it like this…
1. Enter “about:net-internals” in the URL bar (without quotes)
2. Click the drop-down and select “DNS”
3. Click “Enable IPv6”
Since I haven’t experienced an issue with Chrome, I can’t tell you if this will work or not. Let us know!