Would you disable the Kaspersky Protection extension and see if that makes a difference   ? Kaspersky software is known to cause many problems;   slowing down Firefox is one of them. If you have Windows Defender and you are using the safest browser on the planet   (which is of course Firefox) :  it's like you're in Fort Knox   !

Thanks for very useful answer. I dont have windows defender active, it was only Kaspersky extension. The thing is it automatically activate itself after every browser restart. I must say that differences are unbelievable. Just tested with 20+ tabs and there's no problems at all.

Good to see Happy112's advice helped, and that Firefox is now working well for you again.

Security related software often does cause issues with Firefox. Sometimes the settings of the security software needs tweaking to make it work better with Firefox. Sometimes issues may be due to interaction between more than one security product.

I note your system details include details of Firefox extensions:

1. Kaspersky Protection 5.0.141-4-20161031140250 (light_plugin_F6F079488B53499DB99380A7E11A93F6@kaspersky.com)
2. Tamper Data 11.0.1.1-signed.1-signed ({9c51bd27-6ed8-4000-a2bf-36cb95c0c947})

It would be interesting to know what the full name and version is of the Kspersky software is that you are using, and whether it is a free or paid for version. The secnd addon appears to be a standard add-on available form the official Mozilla site

• https://addons.mozilla.org/firefox/addon/tamper-data/

I would expect that to be compatible with Firefox, however I am not sure whether it may be something that could slow down Firefox depending on how it is used.

Hi john, I must say that I'm impressed with Firefox now, i cant remember that it used to be this fast in a years :)

I'm using Kaspersky Internet Security 17.0.0.611 (e) and it's payed. Funny part is that all extensions was automatically installed for all browsers (at least if i remember correct). Otherwise i will get security warnings all the time.

I disabled the second plugin as well since i am using it from time to time when i need to do some tests. Since i got finally good browser speed, i believe it's time to move back to Firefox.

The new Quantum Firefox is incredibly slow! It takes a long time to type anything. Help!

karenreynolds said

The new Quantum Firefox is incredibly slow! It takes a long time to type anything. Help!

You have posted in an old (marked 'Solved') thread, not related to Quantum.

Would you be so kind as to start your own thread  ?

You can do so by clicking on 'Ask a question' at the top of the page and post your own question.

I've another antivirus. old version is working good...i try new version with same computer, but is very very slow. I try to unistall, clean and install and isn't working!

leo19 said

I've another antivirus. old version is working good...i try new version with same computer, but is very very slow. I try to unistall, clean and install and isn't working!

Going to ask you to do what I asked karenreynolds :

See my previous post.

sorry today i'd write a post. if you want to answer....

leo19 said

sorry today i'd write a post. if you want to answer....

You go ahead and start your own thread - click on 'Ask a question' at the top of the page and post a question.

There are plenty of people here who'll be willing to post a reply.

Good luck  !