Top positive review
Slow for a few days, then back to normal speeds
on July 20, 2013
Purchased directly from Amazon. Yes, Macs get viruses, so I decided to get this for my iMac, which I have to keep on an older, unsupported OS (leopard). This also means that my version of Firefox is older and unsupported (but I have to keep the older OS due to several older, expensive software programs on this computer). btw, when I say older, I'm talking 2009 Final Cut Studio, etc.
Norton Internet Security for Mac (also includes NIS 4 for OS 10.4.11-10.6 -- it's in it's own folder in the main install folder, if that makes sense), installed quickly and didn't cause any major issues with my internet speeds. It did seem to load pages a few seconds slower than usual the first two days, but I'm guessing it was "learning" safe sites. Now, everything loads normally.
Norton Internet Security also has a firewall, which seems to be doing a good job of blocking unwanted/suspicious connection attempts.
I delete history, including cookies every time I close my browser, and Norton didn't seem to slow down any future visits to my regular sites (Amazon, banking, etc).
Note: I turn off wi-fi and then turn off Norton if I'm running any processor-heavy programs (e.g. compressor, final cut pro), just to be safe (Norton tends to run in the background sometimes, and I don't want to risk crashing my computer when I'm working on an important project).
Overall, this was $19.99 towards peace-of-mind for when I use this Mac.
Hope that helps =)