Open the about:config page via the location bar and do a search for network.http via the Filter at the top of the about:config page.
You can reset all network.http related prefs that appear bold (user set) via the right-click context menu to their default values.

It is usually not a good idea to change such prefs and such changes can have the reverse effect, especially enabling pipelining for servers that do not support that feature.

• http://kb.mozillazine.org/Images_or_animations_do_not_load

Usually I'd agree with cor-el's advice....it's usually manually-entered values that cause issues. But...

I was experiencing this particular problem and after exhausting all options, posted in the mozillaZine support forum where someone actually suggested that I change the network.http.max-connections setting in about:config from the default value of 256 to 48.

This resolved the issue for me.

After looking into it more myself, it turns out that for this setting Firefox 5 has a default value of 30, while Firefox 6 & 7 (the two versions I've had trouble with) have default values of 256.

I know that being able to make more simultaneous connections can improve page loading times, so I tried some other values. 128 didn't work for me, but 64 does, so I left it at that.

I hadn't noticed that the default of network.http.max-connections has been increased from 30 to 256 and in that case it will indeed help to set that to a more modest value of 30 if you have a slow connection.

The network.http.max-connections-per-server hasn't changed and is still 15.

I found that several network.http settings had been changed, as cor-el suggested might be the problem. I believe an optimization program I use, Advanced System Care, had changed these settings when I allowed it to "optimize" Firefox. I reset all to default and this helped a lot - about half the sites I had problems loading were fixed, but not all. Then tried edamame's suggestion. My problem now is that when I restarted Firefox, all of the values that I had reset to default (mostly having to do with pipelining) AND the max.connections setting all reverted to the altered values! Why would they do this and how do I stop it so settings remain default? I really appreciate the suggestions and feel this is close to getting solved

That can be caused by an extension.

• https://support.mozilla.com/kb/Troubleshooting+extensions+and+themes

See also:

• http://kb.mozillazine.org/Preferences_not_saved
• https://support.mozilla.com/kb/Preferences+are+not+saved

Thank you so much cor-el and edamame. Problem was user.js file which I removed and now everything is zippy again.

You're welcome

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Hi, according to your conclusion , I did set up network.http.max-connections to 32, I tried 64,96,128, 160, 192 but again it started slowing down my FF7.1 again. Default value (reset) = 256

Since I modify network.http.max-connections to 32 ; it seems FF7.1 is now quicker too, on my Windows 7 PC I mean.

I did try many configurations, so far 32 seems a good choice, even if my Broadband connection seems good (12,97 Mbit/s (1,62 Mo/s) ) ; more than 96 max-connections makes my FF7.1 very buggy.

Thanks for sharing.

48 seems to be the highest setting for network.http.max-connections before problems may arise.