If you're having performance issues, this may help:
how do you keep your Macs "clean."
You don't need "cleaner" or "maintenance" apps to keep your Mac running well, and some of these apps can do more harm than good. Most only remove files/folders or unused languages or architectures, which does nothing more than free up some drive space, with the risk of deleting something important in the process.
These apps will not make your Mac run faster or more efficiently, since having stuff stored on a drive does not impact performance, unless you're running out of drive space. In fact, deleting some caches can hurt performance, rather than help it, since more system resources are used and performance suffers while each cache is being rebuilt.
Many of these tasks should only be done selectively to troubleshoot specific problems, not en masse as routine maintenance. OS X does a good job of taking care of itself, without the need for 3rd party software. Among other things, it has its own maintenance scripts that run silently in the background on a daily, weekly and monthly basis, without user intervention.
Other than occasionally repairing permissions
Some people repair, or recommend repairing permissions for situations where it isn't appropriate. Repairing permissions only addresses very specific issues. It is not a "cure all" or a general performance enhancer, and doesn't need to be done on a regular basis. It also doesn't address permissions problems with your files or 3rd party apps.
Disk Utility repairs the permissions for files installed by the Mac OS X Installer, Software Update, or an Apple software installer. It doesnt repair permissions for your documents, your home folder, and third-party applications.
You can verify or repair permissions only on a disk with Mac OS X installed.
Does Disk Utility check permissions on all files?
Files that aren't installed as part of an Apple-originated installer package are not listed in a receipt and therefore are not checked. For example, if you install an application using a non-Apple installer application, or by copying it from a disk image, network volume, or other disk instead of installing it via Installer, a receipt file isn't created. This is expected. Some applications are designed to be installed in one of those ways.
Also, certain files whose permissions can be changed during normal usage without affecting their function are intentionally not checked.
There are times when repairing permissions is appropriate. To do so, here are the instructions:
If repairing permissions results in error messages, some of these messages can be ignored and should be no cause for concern.
