'Not responding' sometimes means the computers CPU is overworked.

You have this problem with two different browsers? What about your other programs?

Start your Computer in safe mode with network support. Then start Firefox. Try Safe websites. Is the problem still there?

http://encyclopedia2.thefreedictionary.com/Linux+Safe+Mode Starting Any Computer In Safe Mode; Free Online Encyclopedia

Hi- yes, both browsers are slow. I started computer in safe mode with networking. Firefox is slow compared to my I.E. 11. I.E. 11 was pretty fast & responsive. What else can I do to try to speed up Firefox? Should I try a clean install of Firefox or maybe reinstall Firefox? I really do not want to loose any book marks or history, etc. as I need to keep them. Do you have any suggestions?

You said the browsers were better with the computer Safe Mode? It could be another program on your system.

As a test, disable your protection programs.

You may have ad/mal-ware. Further information can be found in this article; https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-caused-malware?cache=no

Run most or all of the listed malware scanners. Each works differently. If one program misses something, another may pick it up.

Yes, I did say that I.E. 11 worked better in Safe Mode. Firefox did not. Would you be talking about my Anti-Virus program? I use Avast Free Anti-Virus Program. I did disable it and it does not affect browser speed at all.

Are you using any other protection? How about the mal-scanners?

Hi- I have Windows Defender, but it is turned off & have not used it on this computer for a long time. I also downloaded Microsoft Safety Scanner & ran a quick scan today. That is all I have since computer was upgraded past April from Vista to Win 7.

FredMcD said

Run most or all of the listed malware scanners. Each
works differently. If one program misses something,
another may pick it up.

Hi- I ran most of the malware scanners & absolutely nothing has come up. I am convinced it is the browser. I'd like to know how I can speed up Firefox without loosing my history, favorites, etc. Thank you for very quick responses.

Firefox comes in two or more folders on all computers. They are;

Maintenance: (Programs Folder) <Windows Only> Firefox itself: (Programs Folder) And two folders in the profile of each user on the computer for each Firefox profile for that user.

If you remove the Firefox folder, the user folders would not be affected.

Let's give this a try; Index of /pub/firefox/releases/52.5.0esr/win32-sha1/ https://ftp.mozilla.org/pub/firefox/releases/52.5.0esr/win32-sha1/

Just find your language. (en-US)

Hello- I just downloaded & saved the above Firefox setup, which was 52.5.0 esr.exe (and hope it was the correct one of the two downloads). Now, do I need to remove any files or programs or just what BEFORE I run the setup application?

 Below, is a screenshot of my Firefox Programs.  Do I need to delete anything in any of them?

Thank you

The installer should fine your current profile. Don't worry.

Sorry to say, but that did not speed Firefox up. I can hardly use it right now. What else could I try that would make it work like it use to? Clean install or remove & reinstall or what? Thank you

uninstall Firefox. Then Delete the Mozilla Firefox Folders in C:\Program Files and C:\Program Files(x86) Then restart system. Then run Windows Disk Cleanup. Then run it again and click the button that says Cleanup System Files. Note: your Firefox Profile is saved. But you should make a back up before you do : https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles

Reinstall with Current Release Firefox 57.0.1 with a Full Version Installer https://www.mozilla.org/firefox/all/

If still issues it maybe your profile, make a new one. https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles

Please let us know if this solved your issue or if need further assistance.

but 52.5.0 ESR is. It will continue to get security updates until May 2018, and you can download and install it from this page: https://www.mozilla.org/en-US/firefox/organizations/all/

hgw53t said

...Firefox is very slow to open, hangs, won't respond for a few seconds, etc. I also see a message at times, right above address bar that reads "Mozilla Firefox (not responding)"...

I have an older desktop system (Nov of 2010) with 8 Gigs of Memory.

Check your FF 'Performance' Option and set it like mine if yours is not already. My Windows-7 Paging is set at 3,000 MB (3Gigs). Try that setting (then ReStart computer).

Now, I have a lot of Tabs, so in starting FF, I'll see 'Not Responding.' I Just wait it out. It gets there to complete the loading of all FF windows. Once in a while, I'll see a pop-up about a 'Script Not Responding'. I click 'Continue'. It eventually gets there. I got to clean-up my 300+ Tabs on my main FF window. (Sigh)