My wife's 13" MBP sees pretty light duty - mostly just surfing, iphoto, and office apps. I helped her upgrade to Mavericks, and now it is more beach balls than Spring break. I mean, the beach balls are constantly spinning when you open any app, even Finder, Preview, whatever. Everything still works, but it is all slowed way down. This started immediately after the Mavericks install. It ran fine previous to this install, fast startup, fast shutdown, and no real delays in opening apps. I've read many folks having success getting rid of the beach balls by doing a "fresh install." I make sure she runs Time Machine and CCC (separate external drives) on a weekly basis, so I'm pretty confident all data is backed up. Pardon the ignorance, but will a HD format followed by a clone reinstall suffice as a "fresh install"?