Same question, same rhetoric;
There are several reasons to run antivirus/malware on OS X especially if you are dealing with a mixed environment passing on malicious code even inadvertently does you no favours in the profesional world, let alone family and friends. What does not hurt your Mac & OS X may bring a PC to it`s knees.
You do need to be careful on the choice of application; ClamXav is extremely light and only looks in realtime at what you specify and it`s free. The sentry is presently utilising 0.2% of CPU consuming just over an hours worth of CPU time over several weeks and this is on a machine over four years old. Does anyone seriously still believe that running ClamXav on todays modern hardware impacts performance! The paid for packages I agree are a waste of $ offering little more than a placebo with a heavyweight user interface. ClamAV the parent of ClamXav protects numerous servers globally, which is a pretty good tip...
ClamXav will have no impact on a modern Intel based Mac. To have a free, low headroom, accurate scanner that offers a lot of flexibility and not utilize it seems somewhat stubborn at best. The retorts of AV being a resource hog, boils down to one thing, research; ClamXav will not bog your system down, if it does you have some other inconsistencies that need addressing, or your hardware is so old it`s well and truly time to upgrade, on my Early 2008 MBP ClamXav is simply invisible, there is absolutely no degradation of performance, as for the i7 2.4 MBP & now the Retina MBP it`s completely transparant.
I have literally decades of work on my systems, I have no intention of losing any data, ClamXav is but one tool in a multilayered safety net. Lets face it, if and when OS X is compromised it will spread like wildfire as many fundamentally believe that OS X is invulnerable. I am not entirely sure posts that overly renforce this false sense of security are helpful to the average user, even Apple recognise threats to the operating system and sub components, however the updates are too slow to be considered a preventative measure...
I have never had a positive hit in all the years I have run ClamXav equally OS X is gaining traction and it`s simply a matter of time before someone figures it out, thinking otherwise is simply naive at best. ClamXav cost me nothing monetarily nor time in productivity, this is a safety net that costs little more than five minutes of your time, one of life's better investments.
Virus/malware gains traction by exploiting vulnerabilities on unprotected systems. I don't believe for one second that CalmXav is the single security solution for OS X, it is however the de-facto standard for many mail servers globally (ClamAV), and the app is rapidly updated.
Apple has included ClamAV with OS X server since 10.4 and continues to do so today (
http://www.apple.com/macosx/server/specs.html) with OS X 10.7.3 Lion Server. ClamXav is transparent on an Intel based Mac, adds another level of protection at zero cost.
Apple also clearly list Calmav-137-1 on their 10.7.3 Open Source page (
http://www.opensource.apple.com/release/mac-os-x-1073/) admittedly it is not implemented in the Lion client release, equally I would not be surprised if it was quietly implemented in a forthcoming release of OS X as was XProtect implemented in Snow Leopard. Apple may simply choose to integrate ClamAV into Xprotect and the vast majority will never know the difference. As of OS X 10.6 your Mac is running anti malware like it or not
There are many compelling reasons to run ClamXav and few if any not too, personal choices aside I fundamentally believe that suggesting that OS X is safe to all and does not need such tools is very much a step in the wrong direction; not all are technically minded, neither do all users who may have access to machines follow the rules and guidelines of safe computing. The vast majority simply point and click to get to where or what they want ClamXav simply serves as a barrier to protect those that are unaware and some cases unconcerned, ultimately such safeguards protect the community as a whole.
Be mindful that some of those advising that there is no need for Mac`s to run any form of AV, have already have a high level of computing proficiency and a deep understanding of the system, your kid`s, your grandparent`s, the guy from next door etc likely wont have this acquired knowledge. The premis is to keep the the community as a whole safe, or of course we can all simply ignore the threat and hope that by doing little to nothing, and disabling functionality will do the trick.
n.b. Those that want to run the ClamXav sentry need to download directly from the ClamXav site, as the apps store version does not have this functionality.
Install, dont install it`s down to you now...............