If you have not used Nortons for the last 3 years then you should not really comment as it is not resource hungry as some people state here.... Norton has improved from the days when it was a resource hog, not now.
It is just as good as any other internet security programs, if any all security programs have their pro's & cons, truth to be known they all have their strengths & weaknesses.
I use Norton, kaspersky and Eset on different PC's and find them all OK...my personal choice....have used others but found these 3 mentioned to be above average.
Last comment on memory usage if you are using new computers manufactured in the last 2 years then any internet security programs should not pose a problem unless you are using an old PC with inadequate memory/cpu installed.