Moved this to the General Discussion area for better support. That other thread is old and the software has changed since then. That spike occurring and then sticking shouldn't happen and Technical Support would have been you best avenue for a solution. It's free of charge by phone or online chat and linked under Useful Links at the top of this page - if already there, escalate the issue. They could troubleshoot possible hardware issues or software conflicts. Did it continue if you powered off and back on?
Off the top of my head thinking of possible reasons:
Infection (check software in the last link in my signature below)
Conflicting software (this can get complicated - support is best to advise, but basically anything with active protection)
Incompatible hardware - CPU in particular. (ATOM not supported for one example)
Large quantities of emails stored in Inboxes rather than in sub-folders created to store them - the software will scan them every time it starts.
There are other factors too but support would know best. However, memory peaks should lessen after a while once the software is settled in.
- Mcafee itself had reported no infections and the subsequent install and scan by AVG confirmed no infections.
- As I said, before latest update no problems, then after latest update problems hit. I am not that inclined, being a home user, to chase this one as it is likely not my problem. Given this isn't opensource software I would guess people would expect a good grounded regresssion testing regime.
- Hardware? acer M3970 so no, not Atom. And implicitly no as it has been running prior to most recent upgrades.
- Emails? Wow, have users do something to help the software cope.
- Memory leaks should not be released, generally poor testing and quality control, not something user need put up with. Settles in? Wearing in is a mechanical hardware thing. Software doen't "settle in".
Support were in denial when I approached. To me as removing the software has definitely fixed my computer problem. Not worth pushing my end as AVG seems fix the problem.
As I said support are the best people to troubleshoot this and if at first you don't succeed with them, simply ask them to escalate the matter. But as you seem OK with AVG then good luck. Hopefully others will post their experiences to compare with yours but I personally haven't seen this.
The email storage tip was more for CPU cycle-saving really as it's an old issue going back years with most antivirus products.