Security Update 2015-001 is recommended for all users and improves the security of OS X.

This update includes the following improvements:

  • Resolves an issue that might cause Wi-Fi to disconnect
  • Resolves an issue that might cause web pages to load slowly
  • Fixes an issue that could cause Spotlight to load remote email content when this preference is disabled in Mail
  • Improves audio and video sync when using Bluetooth headphones
  • Adds the ability to browse iCloud Drive in Time Machine
  • Improves VoiceOver speech performance
  • Resolves an issue that could cause VoiceOver to echo characters when entering text on a web page
  • Addresses an issue that could cause the input method to switch languages unexpectedly
  • Improves stability and security in Safari