Necessity of File System Protection?

Two questions:

1) Has anyone benchmarked the difference between have the file system protection turned off and on. You know maybe loading photoshop and editing and saving a few photos, or copying a couple hundred files from one directory to another. I'm a performance freak and don't like the idea of every file I access having to be scanned due to the performance decreases.

2) Is there a way in version 3 to limit which drives the file system protection protects? I'd have it just protect all drives except my hard drive (CD drive, USB memory cards, network drives). But there doesn't seem to be a way to do that I can find. Only to exlude file types?

For years I always had the file system protection turned off. Nowadays, any new external file comes from either a software CD from a reputable company like (Microsoft Office software) or from a website or e-mail (attachment). So my machine has never gotten any virus until recently, get this, a friend of mine bought one of these 4GB memory cards that plug into your USB port. He swore he never plugged it into any machine before mine, had just broken it out of the package. We were going to copy a bunch of my photos to it. It's one of these stupid things that autostarts a menu with a bunch of software utilities on it that you can run (and can't remove). A day later, my daily scan caught a virus on my machine! I was at a loss at first as I NEVER had a scan find a virus before and was wondering how the hell it got on there as I don't have a floppy drive and hadn't stuck any CD's in my PC lately. So I get to thinking the only thing out of the ordinary I've connected was that dang 4GB flash drive. So I stick it in and scan it and low an behold the autorun file is infected! How the heck can a company release a product into the market with a virus on it?! I forgot the brand. I'm still not sure I believe him that he never stuck it in any other computer as I didn't witness him take it out of the package and it didn't look like a hokey brand if I recall.

 

It isn't difficult to buy an infected USB device. Block autorun on all and every drive = problem solved.