Cocktail

It is primarily designed to run a variety of routine system maintenance tasks which in Unix typically run at around 3 am. Most of us shut our machines off or put them to sleep overnight and if you do these tasks never get run. Over time, your machine could, in theory, begin to slow down without routine maintenance being done. You would not notice anything over the short term, however. This is by no means the only utility which performs these tasks. It will also clear caches, log files and repair permissions if you elect to do so. I have found it to be safe and reliable. I have mine set to run weekly automatically.

There are also a number of interface tweeks available under the Interface tab which are interesting. So, I have found it useful.

 

Exactly. If you think you need some of this stuff, Onyx is free. You will see the same results = nothing.

Same with stupid "did you repair your permissions?" crap. ugh. does. nothing. waste. of. time.

And look at all the ones I get to ignore: [support.apple.com]

OSX does a lot of it on its own.