hi, other users have reported that this issue was caused and could be resolved by adjusting the settings of their norton software running on affected systems: https://support.mozilla.org/en-US/questions/1048938#answer-696520

Sorry, but the answer given is not clear. The article mixes up Performance Monitoring exclusions with Auto-Protect Real Time Protection exclusions.

I am not prepared to mess with Auto-protect in Norton.

Some added toolbar and anti-virus add-ons are known to cause Firefox issues. Disable All of them.

This is all unsatisfactory. I HAVE added Mozilla folders to the exclusion in auto-protect real time protection, and, yes, Firefox now opens in under 1 second. However, this is totally unsatisfactory because: 1. Mozilla and Symantec Norton should be better professional companies that should have sorted this out/be sorting this out so USERS don't have to make these exclusion changes; 2. not all users are competent to make these changes. Many users are not computer literate at that level. So, Mozilla & Symantec are basically saying "use another browser". 3. the problem as witnessed infers that Mozilla developers are NOT testing thoroughly enough. That is unprofessional.

Since Norton is causing that problem in Firefox, have you tried Norton support for answers?

https://community.norton.com/en/forums/firefox-extreemly-slow-start

Bottom line is that Mozilla builds Firefox , and provides multiple pre-release development versions over 18 weeks that can be used by developers to test their add-ons before release. Then other companies add on to Firefox at the time of release, or before if that company does beta testing with their advanced users. Norton is the one that created this issue for their users, and they need to fix it; although it could be caused by Trusteer Rapport being used with Norton, as mentioned in that Norton support thread. If that turns out to be the case Norton has to work with Trusteer to get it fixed.

I don't agree. There is no evidence that Norton changed anything. It was the new version of Firefox that had the problem, not a new version of Norton. I have N360. Therefore, at least one, if not more, of the testers of Firefox should have been using it in conjunction with N360. I repeat, Norton did not cause a problem BEFORE the latest release of Firefox. This issue was cause by Mozilla.

I found that the installed version of Trusteer Rapport was not compatible with the 36.0 from one of the forums. Many banks recommend that you install this program for added security but I don't think any require it. I uninstalled the version and Firefox loads fine now. I did go to the Trusteer Rapport site and IBM acknowledges the incompatibility and they have issued a fix. I am a bit reluctant to reinstall until I see if others are satisfied with the fix.

That was very good work. Well Done. Please flag your last post as Solved Problem so other will know.

Still isn't solved for Despairingly, the "owner" of this thread.

"I don't agree. There is no evidence that Norton changed anything. " Whether you agree with me or not isn't the point. Norton better have changed something, as add-ons which are installed by Security Suites like Norton need to be updated for each new version of Firefox that is released.

Based upon past experience by many Norton users, you may need to run the Norton Live Update repeatedly until all the updates are installed. That Live Update is notorious for not installing all updates without a little "prodding" from the user.