How about on OS X?

I work at a helpdesk, and every one of our machines /must/ have AV. Even the Macs. Symantec admits never having found an OS X virus at all, but they still scan everything, with huge impacts on performance. The latest version has no configuration, and no way to disable auto-protect, and that is the only version that works with OS X 10.4. It will scan every single volume when mounted, it will scan a user's home directory every time they log in, and it will stop everything on the computer when it has found a (Windows) virus, until you click the "ok" button.

When it scans a mounted drive, it is normally slow enough that you can actually open the thing and start running programs before the scan starts. Then it doesn't respond to cancel for a while because it isn't threaded nicely. In addition to that, it'll scan its own installer, which I just find comical.

The home directory scan is just way too much burden for login time, when loads of other programs are already trying to auto start. And there are no OS X viruses.

Lots uf our users (used to) use Eudora, which will save every attachment to a directory on recipt of the message. If the virus scanner tried to quarantine the file while Eudora was open, everything on the whole computer would die. I've had to go into single user mode to fix that.

Plus when a user with a Eudora attachments folder is migrated, thye may have loads of Windows viruses laying around from before we had an MTA level virus scanner running. The file copy will pause each and every time it finds a virus (not like the Windows versions, which will just keep adding new discoveries to a list) until you hit the "OK" button. It doesn't want you to make a decision, it just wants to alert you about something. Good thing it waits for user input to keep going

On one migration I got bored halfway through so I started keeping a tally. I recorded well over 200 Windows viruses, which is probably less than 2/3 of the total number. I had to click the button 300 times, so I was required to sit at the computer for the duration of the file copy, instead of going off to do something useful.

We have quite a few of the original Core Solo Mac Minis (512MB of ram too!) which are slow enough by themselves. With auto protect running in the background it can take up to 2 minutes to open a small PDF while the computer isn't doing anything else. Thats just short of insane.

Also I used to run the Coporate / Enterprise Windows versions, but when I saw that it scanned my Winamp settings file every time Winamp accessed it (many times per second) I decided that it needed to go. Especially since it kept turning auto protect on mysteriously after I disabled it.

- Nexox