I never EVER though of installing Norton AV as it was a resource hog in the past before 2009 and that image stuck in my head. I heard people always say that since 2009 it started becoming really light and is the gamer's AV of choice.
I ignored it and continued to use NOD32 Antivirus.
After NOD32 upgraded from v4 to v5, and from v5 to v6, it became more and more bloated. Even restating my computer with NOD32 adds 5 to 8 seconds more than when I measure it with Norton installed
NOD32 - 30 seconds full reboot time
Norton AV - 24 seconds full reboot time
So I started buying licenses for other products such as Bitdefender AV and Kaspersky AV due to their high ratings they get on AV comparatives and other virust testing labs.
I never thought of Norton at all mainly due to the fact that they do not even participate in these tests so I thought there must be something they are unsure about...
until recently, I saw a test ( http://www.passmark.com/benchmark-reports/ ) that was mainly focused on AV performance and Norton shined in it
Being sick of the bugs in Bitdefender AV and the slowness of Kaspersky, I deviced to buy a 1 year license for Norton AV and I was shocked by how snappy my system felt, it's as if I was running no AV at all yet I was!
It has also blocked a few threats for files I have downloaded and based on the latest tests I've seen in that performance test, I know I am well protected as Norton did very well!
I just also came to know about Norton's Smart definitions and read about it and was impressed about the techonlogy Symantec uses in this awesome lightweight product!
I must admit a Norton AV license costs more than the competition but I think it's worth it if you are like me wanting good protection at no performance expense
My only suggestion to Symantec is to start participating in those AV tests online because many others I se on other forums don't even want to try the demo of NAV being scared that they are not good with protection or virus removals.
Matrix Leader