Firefox 12 is very slow and machine slows down

I have recently installed Firefox 12 and the problem that I am facing with the same is that it is starting up slow and loading the web pages slow as well. I was not having any such issues before with the previous version of the Firefox that I was using. When I am opening Firefox the system starts running slow as well. I am not able t make out if this is an issue with the Firefox or my system. The system runs fine when I am opening other application, this issue seems to be somewhere with Firefox. Is there anyone else who has faced the same and has an idea about this issue and can suggest me some workaround for fixing it?

Before I suggest you something about the same I just wanted to know have you tried out the below basic trouble shooting:

• Try running a full system scan and see if any virus is getting detected.
• If that does not help then try disabling all Addons and Plugins
• You can also try out uninstalling and reinstalling Firefox as well.
• If you still do not have any luck with these solutions then clean the registry using some cleaner and reinstall Firefox.

Just try out these things and let me know if the issue is getting solved or not. Best of luck.

You can very well try out the above solution but if they are not helping then you can try creating a new Firefox profile. For that you can refer to the below steps:
First open "Start" menu> "Run"> and type the below commands:
firefox.exe –profilemanager
firefox.exe –P
If in your case you are having different version of Firefox then you will have to make use of full path with quotation for e.g.
"C:\Program Files\Mozilla Firefox\firefox.exe" –P
"C:\Program Files (x86)\Mozilla Firefox\firefox.exe" –P
These are the default installation directory but if you want to check out the executable file location then just right-click on the desktop from the Mozilla program and select Properties. You can copy the Target location by going to the "Shortcut" tab.

You can also create a new Firefox profile on Windows by following below steps as well:
Close Firefox go to Start Menu press "windows key+R" enter firefox.exe -P (i.e., firefox dot exe space hyphen P) click on ok and then click on Create Profile button. When the 'Create Profile Wizard' window opens up then click on Next and enter a new name in Enter new profile name' box and click on Finish. When you are done with the same then make sure that you are unchecking "Don't ask at startup" box and select new profile and then click on Start Firefox' box.
Just try out the same and see if it is helping.

So now I have tried running a full system scan and no virus were detected. I have tried disabling all Addons and Plugins and have also tried uninstalling and reinstalling the same and even that’s not making any difference. I have cleared the registry using registry cleaner and have not got any help from it as well. Other than this I have tried creating a new Firefox profile following the above mentioned solution and I am still not having any luck. Is there anything else that I need to check out or any solution that I can try out further?? Any help regarding the same will be highly appreciated.

Have you tried trouble shooting the Firefox in Safe Mode, if not then try out the same and see if it is working fine there:
You can start Firefox in Safe Mode by holding down the shift key when starting it. When you get Firefox's Safe Mode window then click on Continue in Safe Mode button. In safemode any customizations that you might be having will be changed to their defaults, the extensions and themes will be disabled as well. You don’t have to worry about the same as these changes are temporary and they will return to their normal state when you will start Firefox in Safe Mode.
Just try it out and post back the result that you get so that I can have a better idea of the issue that you might be having.

I think there is seriously something wrong with the Firefox 12. I mean now I have tried trouble shooting the Firefox in Safe Mode as well and I am still getting the same response. It is still starting up slowly and taking more time to load the pages. I also wanted to share that I have checked about the same issue on web and have tried other suggested solutions like turning off hardware acceleration, setting no proxy" in the lan settings, installing the latest update for the Graphics driver as well as for Windows. Disabling the antivirus program that I am having but no matter what I have tried so far they are just not making any change. I have currently switched back to firefox 11 and I am not having any such issues with this. Anyways I will still like to know if there is any other solution rather than the ones that has been mentioned here for fixing this issue in Firefox 12. So if anyone is aware of it then please share it here, it will be very grateful, thanks in advance.