Norton toolbar and firefox slowness

The issue I have is, Firefox 28 and 29 run slowly, and stutter when watching videos.  I just assumed it was Firefox.  Checking support, they stated to run Firefox in safe mode, which disables add=ons and extensions, then turn each one on and check for the issues I was having.  I find that leaving Norton Vulnerability protection on, and disabling the Norton toolbar seems to work for me so far.  My question is, will I still be warned about dangerous sites, and will attacks still be blocked without the toolbar turned on? 

I have been testing Chrome and have no issues in speed at all (Norton toolbar is not turned on in Chrome...I couldnt get it added as an extension/add-on).

Thanks in advance.