Hi there StaticDrift!
I personally think that Norton Internet Security is (very) heavy on your system.
I have tried many antivirus softwares before and I found that Kaspersky Internet Security 2015 is best for gaming.
It is paid, but it's a very good antivirus if not the best in my opinion.
It has settings such as
"Gaming Profile" so that it doesn't bother you and
other settings to concede computer resources to other parts of your PC.
I have Kaspersky Internet Security and you can get a key for as little as $15-20 from Kijiji or eBay, since it sometimes comes with some computer purchases.
Let me know if you have any questions.