Firefox contains built-in Phishing and Malware Protection to help keep you safe online. These features will warn you when a page you visit has been reported as a Web Forgery of a legitimate site (sometimes called “phishing” pages) or as an Attack Site designed to harm your computer (otherwise known as malware). This feature also warns you if you download files that are detected as malware.
I have not had any problems with firefox on my computer and IOW site. Sometimes systems run slow if there is a lot of activity on them. Yesterday my computer ran in 13 updates for my windows 7 around 3pm EST and than ran 12 more updates when I logged off around 7:30 pm. I do delete my history and "cookies" about once a week. My tech guy at the school where I teach told me that helps get the "gunk and junk" out. He explained like having a water softner, you need to back wash the resin bed ever so often to make it work, once the bed is filled with ions it will not work. I have only had one problem ever with a virus and that was about 3 years ago. I never open attached e-mails unless I know who sent them and I knew they were expected and I do have the best antivirus program I know.
Found this on a anti phishing site about a Google update Dated today
@stopbadware
August 14, 2014 - 13:48 — Google will expand Safe Browsing warnings beyond #malware to warn users about other kinds of deceptive software http://t.co/CwUpBOEA2u