Try enabling hardware acceleration. You can do this by clicking menu>options>advanced and then check the box that says enable hardware acceleration when able. You can also try refreshing Firefox by resetting add ons. I would just write down your favorite add ons and try that, I just did it today and it was very noticeably faster.

Have a great day!!

Jon

did both before posting question neither made any difference

Try enabling an new HTTP cache. To do so, enter about:config into Firefox's address bar and press Enter. Search for the browser.cache.use_new_backend flag and double-click on it. Change its value from 0 to 1 to enable the new cache. ... Close about:config and continue browsing—no need to restart or anything.

-Jon

does not work get The address isn't valid

This about:config works on Firefox on my laptop but on my Surface were I have the problem I get as I say above "The Address is Invalid" and cant get to the config page

See this forum thread in the Norton forum: https://community.norton.com/en/forums/firefox-extreemly-slow-start

I have this on my Surface and Alienware Laptop both also have Norton and the problem is on the Surface

rephil said

Fire fox out of the blue started to take a very very long time to load I have done a reinstall and a refresh niether work.................

I also have the same issue. There is definitely a problem with v. 36.0 AND 36.01. I have reinstalled v.35.0 and there is now no problem. Load times are back to 2 secs. MOZILLA PLEASE SORT THIS OUT.

thanks for the info about version 35 reinstalled that version now all is fine

Same problem - reinstalled 35.0 and ok now.

Except it automatically updated to 36.01 again - Changed my update options and re-re-installed 35.0.