by 
Apple has released iTunes 11.1.3 for Mac. The 11.1.3 update doesn’t see any new features, but it does fix the annoying bug where the equalizer doesn’t always work as expected. It also adds performance improvements when switching views in large iTunes libraries. From the release notes:
iTunes 11.1.3
This version of iTunes resolves an issue where the equalizer may not work as expected and improves performance when switching views in large iTunes libraries. This update also includes additional minor bug fixes.
Note: If you are using OS X Mavericks, your book library can now be found in iBooks for Mac.
For information on the security content of this update, please visit: support.apple.com/kb/HT1222.
Users can download the iTunes 11.1.3 update via Software Update on their Macs.
Apple releases iTunes 11.1.3 with equalizer and large library performance improvements originally appeared on TUAW – The Unofficial Apple Weblog on Tue, 05 Nov 2013 19:00:00 EST. Please see our terms for use of feeds.
Source
