A possible cause is security software (firewall,anti-virus) that blocks or restricts Firefox or the plugin-container process without informing you, possibly after detecting changes (update) to the Firefox program.

Remove all rules for Firefox and the plugin-container from the permissions list in the firewall and let your firewall ask again for permission to get full unrestricted access to internet for Firefox and the plugin-container process and the updater process.

See:

• https://support.mozilla.org/kb/Server+not+found
• https://support.mozilla.org/kb/Firewalls

Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance).

• Do NOT click the Reset button on the Safe mode start window or otherwise make changes.

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

Thanks for your response. I have tried what you suggested but no change. I have also disabled all plugins, no change and tried starting in safe mode, also no change. I have even turned off my firewall completely which also made no difference.

Try to boot the computer in Windows Safe mode with network support (press F8 on the boot screen) as a test to see if that helps.

Hello,

I've tried all your recommandations and nothing changes for me too. But i have an idea about the causes of the problem. At home, the version n°18 of Firefox is fast but not at my office. The only difference is that at my office there is a proxy and all the internet communications are established through this equipment. Don't you think this is the reason of the speed problem in your new version of Firefox ?

Probably you are correct math3140. But if so then there seems to be nothing i can do to solve the problem if i stick with the latest "improved" (what a joke) version. I have spent 2 days trying everything imaginable to resolve this issue but to no avail. Thank god i finally have it sorted out. It took some doing but eventually i was able to find a version 17 to download and guess what? Everything is running perfectly once again at proper speeds. I'm sick of being hassled into updating things that don't need to be. I don't use "social networking" sites, i have a real life so i couldn't give a rats about upgrades to accommodate them. I shall rely on Bitdefender to protect my pc's integrity and keep using version 17 which is what works for me. I appreciate the help offered here but am over the unnecessary complications that are forced upon users by "upgrades". I am not some tech guru, i'm just an average Joe who wants to use the net without having to take an I.T. course just to understand how to get my computer working like it always did.

Hello,

Is there a member of Mozilla to bring us some help please ? Or just tell us that you're checking the problem ?

Thank's a lot

I`ve used Firefox for years so I know what to expect. A few days ago it virtually stopped and no quick fixes sorted it. I uninstalled and re installed. Still not much better so I reset and today when it opens it just freezes. All this time Chrome is working OK. Now on the restart it seems to be at normal speed. With all these known problems and nothing seemingly being done to help I`ll likely go to Chrome as my default even although Firefox design beats it all the way. Please somebody FIX IT