With update to Norton v 18.5 my two personal computers (both running Windows 7) started work a bit slow (especially boot time) . It seems to be that Norton was the culprit because if I uninstalled Norton the problem went away.
In Norton 2011 I see something that I reported as a bug when it was just released and it seems it not a bug but design. Norton seems to "call" the Cloud whenever it detects a threat on the computer no matter Auto-Protect or Download Insight.
E.g. I unpack archive with 5 malicious files , Norton detects 3 of them - files are removed but Norton displays Auto-Protect is processing threats . It stays like that at least minute or two and then displayed another pop-up Auto-Protect has removed threats . Your computer is secure.
When the first message is displayed , CPU goes higher than usual. This was not like that in version 2010.
Our company is Symantec partner and we (re)sell Norton boxes . When we install Norton on client computers (old PCs) with less resourses - e.g. 512 Mb RAM or 768 Mb RAM , or old processor - Norton feels extremely high on these computers (unlikely on new modern current computers).
So , I wanted to say - please , keep Norton as light as possible - refrain from making changes and features that migh slow down even the old computers because big part of your clients run old computers. In case Norton becomes high on resourses I am sure many will dump the program.