Apple has released the OS X 10.8.4 Mountain Lion update which comes with several bug fixes and performance improvements to the platform. This update has been in beta for some time despite only bringing improvements and no new features. In any case bug fixes are always welcome on any platform and we recommend that you get this update as soon as you can.
If you have a supported device you can download the update for free through the Apple App Store if you have OS X Mountain Lion installed.