Recently, my Mac-mini (2013, OS Mavericks) has been running slow, some youtube videos stutter and are out of focus. On my hard drive I found a folder "Narlabox". I googled Narlabox, found only four sites, but none that specified Narlabox. Thinking it might be something evil I trashed Narlabox. However, the Mini still runs slower than it did months ago. In Safari preferences I checked for extensions, I have zero extensions. Should I delete all cookies, plug-ins, etc.? The mini does not have Norton's anti-virus, so I can't check everything that might be causing problems. I appreciate all suggestions.