iMac(late 2012) Overheating

There are no viruses for OS X, immediately uninstall all antivirus apps following the developers instructions. OS X does not require third party utilities to run well, no antivirus, cleaning, or other third party utilities.

You did not indicate why you think your computer is overheating, could you be specific pleas?

IT might be overheating but I doubt that is your problem. after uninstalling the anti-virus reset the SMC and PRAM 2-3,times. If the problem persists Google EtreCheck and post a report of your system.

You should not use things like SMC Fan Control to change the behaviors of the fans. If the computer is actually overheating (in which case it would shut down unexpectedly once going above a certain temperature), the issue is a hardware problem needing repair, and trying to address it by fiddling with the fan behavior may result in damage to your hardware. If it's not actually overheating, just let the fans operate as designed.

If you think there may be a hardware problem, contact Apple. They can examine the machine and figure out where the problem is.

The question is, is the lagging happening because the machine is hot (which could mean there's a hardware problem), or is the machine getting hot because of whatever is causing the lagging? If something is really hammering the processor when the machine starts to get hot and lag, that may be causing both problems.

There most certainly are viruses and malware for OS X.

Some of the vulnerabilities are in 3rd party apps like Word or Java. The others attack the OS directly.

A few examples:

https://nakedsecurity.sophos.com/2012/03/30/mac-malware-backdoor/

http://www.thesafemac.com/dr-web-announces-new-iworm-malware/

http://www.thesafemac.com/new-wirelurker-malware-infects-mac-os-x-and-ios/

http://www.thesafemac.com/new-ventir-malware/

There is a very small amount of malware but zero viruses. The malware can be EASILY avoided by using common sense, meaning:

Never download from a torrent.

if you get a pop-up, ad, e-mail or phone call advising your system has been compromised those are scams.

Keep OS X up to date

If users follow those simple rules and do not install worthless antivirus, cleaning and othe OS X maintenance apps their machines will normally run fine for years!

Andrew_Debbie wrote:

A few examples:

Every single one of those examples are no longer active, as they have been blocked by Apple's anti-malware protection in Mac OS X. They can all be considered extinct at this point. There is currently no known malware capable of infecting an up-to-date Mac OS X system. Malware that is unknown may or may not exist, and there isn't a tool out there at this time that can protect you against such unknown malware.

Malware definitely is not involved in any way with the problem being described by arcaniko. There could be involvement of adware, but without mention of any adware-related symptoms, there's no reason to go there at this point.