This issue started a few days ago.

Firefox 6 started having trouble loading pages, especially pages with large numbers of connections, and once I have several tabs open. The pages will keep trying to load, but data stops getting to the browser.

I can "reset" the browser by closing it and reopening.

It's not a connection issue: Chrome on the same system has no issues.

I have completely removed and reinstalled the browser, and have tried the latest stable beta, and the issues persist.

I use news.google.com regulary, and due to the high number of connections, once I've loaded this page I cannot load any other pages. Also, if I open several tabs simultaneously it'll have the same problem.

UPDATE more details and troubleshooting steps taken so far:

I disabled and removed each plugin in turn and tested the browser: especially with aggregation sites such as news.google.com, pages will either take forever to load, will not load at all, will load once and then not reload, or any combination of the above.

Then I removed Firefox completely using RevoUninstaller and deleted the Mozilla folders in the Appdata directories in the user profiles and the Mozilla and MozillaPlugin trees in the registry. Total uninstall. Then reinstalled with the latest, 7.0.1 or something like that. Same exact issue.

The one other thing I was very loath to do was to do a system restore. However, my system restore apparently only goes back a week or so, and this issue has been going on longer than that. So no dice.

The issue seems most problematic when I try to load multiple pages at once, which I do frequently. If I wait for pages to load before starting the next page it doesn't have as many issues. Pages with lots of different sections like ads or social media integrations or other things that would tend to pull from many different domains tend to have the most problems.

UPDATE system info and further details:

I also have Chrome and IE9 installed on this Windows 7 computer, which is running 8GB RAM and a current Intel CPU. The system is less than a year old, laptop, touchscreen, from HP.

The number of tabs does not seem to have a particular effect, except when those pages each load large numbers of items from different domains. For instance, news sites that load social network items and ad items and in general seem to be the ones loading the most from different domains seem to be the most problematic. So long as I only load one or two at a time it's not an issue. But once I try loading several simultaneously or add a bunch before one completes loading, it'll trigger the problem.

Sometimes the problem is just extremely slow load times. Other times it's completely dead stopped connection with no data moving at all to and from FF. Other browsers are not effected.

  • I've recently (over the last 3 or 4 months) started seeing the same thing, but this is on Firefox 14.0.1 Chrome loads the same sites fine. Restarting FF seems to help for a while. I've looked at the about:config values mentioned by @tom-wijsman below and increased them. I'll report back if this fixes things. Aug 18, 2012 at 12:21

2 Answers 2


Under about:config, inspect the following settings:

  • network.http.keep-alive
  • network.http.keep-alive.timeout
  • network.http.max-connections
  • network.http.max-connections-per-server
  • network.http.max-persistent-connections-per-proxy
  • network.http.max-persistent-connections-per-server
  • network.http.proxy.keep-alive

Check out TCP Optimizer as well as other handy things on that page related to connections.

Perhaps Firefox and Google Chrome are implemented slightly different resulting in a different experience, Google Chrome might properly release connections it doesn't need to keep established whlie Firefox keeps them open for a longer time. Perhaps some update changed a setting somewhere. You might also want to check the event log, the history of Windows Updates and your network adapter driver and settings.

Use tools like TCPView or netstat to figure out what exactly happens with the connections, try to compare them between Firefox and Google Chrome to see what happens for both. You can also use Fiddler2 for more detail on the HTTP level and Wireshark for more detail on the Packet level...

  • I'll check these out. I've tried to determine what sort of patches may have caused this, but by the time I got around to doing that it had been too long and the roll-back history did not go back that far. I run FF, Chrome, and IE9 on this system and only FF has this issue as described. Nov 14, 2011 at 15:09
  • All of these are within the normal/expected and default ranges. I have not modified my browser configuration beyond the plugins installed and as you see from the problem description, I've completely eradicated the plugins in testing this issue. Feb 6, 2012 at 16:55
  • Whoa, still experiencing this? Have you tried to create a new browser profile, a new user profile or reinstalling the browser or OS altogether? Especially a new browser profile when you haven't tried that should be a good start... Feb 6, 2012 at 16:59
  • 1
    See the OP. Already dealt with all except the OS reinstall. I'm pretty sure it's an OS/Driver issue, but it's my wife's computer and she uses Chrome, and since last updating I got a new job that included an iPad and iPhone and so I'm not really using the computer any longer. I plan on doing a reinstall sometime this year on the laptop and will report back if that resolves the issue. Feb 6, 2012 at 17:03
  • I'll just mark this as the solution as I haven't gotten around to a reinstall and the issues really isn't an issue any longer. Not that it's solved or gone away, but on the principle of "out of sight, out of mind". Aug 22, 2012 at 13:48

You might have run into memory problems which FF 6 still manages quite badly. You can check this using Task Manager, Processes tab, menu View / Select Columns, and add "Memory - Working Set". Please let us know how much memory FF is consuming when a problem occurs and how much RAM you have available.

You can also try another browser, such as Internet Explorer or Chrome, to see if the problem is specific to FF or you are reaching some limit in Windows. It would also be interesting to know if you are having this problem when booting in Safe mode.

  • Harry, I'm sorry, I didn't include that I already have Chrome and IE9 on the system and they are not having any issues. Also, I have more than enough system memory and the number of browser pages or plugins running does not seem to affect the issue. Nov 14, 2011 at 15:22
  • I would still try to have a look in Task Manager or in Event Viewer for some trace of a problem. Let me know how it goes.
    – harrymc
    Nov 14, 2011 at 15:52

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