I have found that Firefox loads pages very slowly or not at all since an update to AVAST Free antivirus. I have identified AVAST antivirus as the culprit as pages load at the expected speed when AVAST is disabled. I followed the recommendations in this article [http://www.makeuseof.com/tag/5-firefox-runs-slow-browsers-run-fast/] and none was effective till I disabled AVAST. The only other issue that I can find is that Firefox has disabled Adobe Acrobate plug-in because it is out of date (version: 11.0.10.32 and vulnerable) and I am unable to update it because Firefox will not permit me to do so. Please advise me if I can fix this or if I need to refer to AVAST. Thank you.