Very slow buffling after changing a software from Norton 360 to Norton Internet Security

Question

When I download movies using "Norton 360", it doesn't take long time. But when movies are downloaded, using "Norton Internet Security", it takes 10 times longer. (For one-hour movie, it takes more than 2 hours to watch it, waiting for very slow~ download/buffling).

Answer 1

Antivirus software is NOT needed if the Mac you are running is only running OS X. Antivirus apps interfere with normal performance and operation of a Mac because they program too many controls into the main OS X system software impacting general performance of your Mac.
Here are some of my tidbits of advice on how to avoid viruses in the future, if you encounter a virus, again.
Some anti-virus solutions can slow down your Mac, but to be honest, the best anit-virus app is you, the user and your brain.
Don't visit questionable websites or website you are unsure about.
Don't use Torrents or engage in "Torrenting"
Don't install pirated software or software downloaded from a questionable or unknown websites or untrutsted sources.
Java is still a vulnerability concern,  if you do not need it, don't use it.
Use a browser filter and pop-up blocker
Don't open email attachments from email addresses that you do not recognize.
Install security updates when they become available
Educate yourself as to what threats are common and active.
In effect, use your own brain as the antivirus filter.
Follow that advise and in MOST cases, you will be fine and won't risk your Mac to potential Trojans, malware or viruses.
If you feel you need some baseline virus protection that is minimally invasive on the Mac OS X system, install
ClamXAV
http://www.clamxav.com/