I'm somewhat convinced my mid-2010 MBP is going to bite the dust sometime soon. Hard locks are getting more frequent and the thing crashes most apps and goes unresponsive at least twice a day. Using the guest account seems to run a lot faster/smoother, which makes me wonder what it is on my admin account that's making things unstable. I don't know if the issue is caused by Mavericks but it seems to be more common since I upgraded.
I think I recall the general consensus being that formatting/fresh installs don't benefit Macs the same way they do PCs, but would it be worth trying as a last resort? I've upgraded every OS version since Snow Leopard, and each time the performance dipped (although Mountain Lion was slightly improved over Lion).
Co-signed. Alfred's fantastic, been using for years. I don't remember the last time I clicked to launch an app.
I always do a clean install every other OS version. It'll make your Mac feel a whole lot snappier, no doubt, especially if you take the time to do a cleaning and get rid of crap you don't need if you manually migrate stuff back.